CHAPTER I

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HYPEREMIA: ITS CONSEQUENCES AND TREATMENT.

The reactionary results of injury to various tissues and the first local appearances due to the surgical infectious diseases are indicated by certain appearances, which, for a few hours at least, are in large measure common to both. Their beginnings being pathologically similar, their results depend not alone on the violence or intensity of the process, but also, and in predominating measure, upon the primary influences at work. The consequences of mere mechanical injury--such as strain, laceration, etc.--are in healthy individuals promptly repaired by processes which will be taken into consideration in the ensuing chapters. They are throughout conservative and reparative, and are directed toward restoring, as far as possible, the original condition. The consequences, on the other hand, of the surgical infections are more or less disastrous from the outset, although the extent of the disaster may be localized within a very small area, as after a trifling furuncle, or they may be so widespread as to disable a limb or an organ, or they may even be fatal. It is of the greatest importance, not alone for scientific reasons, but also because treatment must in large measure depend upon the underlying conditions, to differentiate between these two general classes of disturbance, which we speak of as--

A. _Those produced by external or extrinsic disturbances_, _i. e._, traumatisms, sprains, lacerations, etc.; and

B. _Those produced by internal and intrinsic causes_, which, for the main part, are the now well-known microörganisms, such as cause the various surgical diseases.

These latter disturbances may be imitated or _simulated_ in the presence of certain irritants within the tissues, such as the poisons of various insects and plants; the irritation produced by foreign bodies, minute or large; and possibly the presence within the system of certain poisons whose nature is not yet known, such as that of syphilis, or certain others whose chemistry is fairly well understood, but whose presence cannot be easily explained, as uric acid, etc.

Clinically, all these disturbances are manifested by certain phenomena common to each, which may present themselves at one time more prominently, at another less so. These significant appearances have been recognized from time immemorial as the _calor_, _rubor_, _dolor_, _tumor_, _et functio lesa_ of our ancestors, or as the heat, redness, pain, swelling, and loss of function of our common experience. When one or more of these are present, the surgeon cannot afford to disregard the fact, while he should, moreover, be able to account for each on general principles which should to him be well known.

To their more exact study we must, however, make some preface in the way of general remarks concerning a phenomenon everywhere easily recognized, but as yet incompletely understood. This phenomenon has reference to an undue supply of blood to a part, and is commonly known under two terms which are practically synonymous, namely, _congestion_ and _hyperemia_. To begin with these, then, we must note, first of all, that congestion and hyperemia may be--

A. _Active_; and

B. _Passive_.

They may also be spoken of as--

1. _Acute_; and

2. _Chronic_.

Considering first the two latter distinctions, it will be found that the acute hyperemias are met with most often in consequence of sharp mechanical disturbances. The chronic hyperemias, on the contrary, are conditions which in many individuals are more or less permanent. Note accurately here the proper significance of certain terms. Hyperemia means, in effect, an oversupply of blood to the given part; the term should have only a local significance. When the entire body seems to be too well supplied with blood, the condition is known as _plethora_, the counterpart of which term is usually _anemia_. The direct counterpart of the term _hyperemia_ should perhaps be _ischemia_, meaning a perverted blood supply in reduced amount. With plethora and anemia as terms implying general conditions, with hyperemia and ischemia implying local conditions, there should be little room for confusion in phraseology.

The active form of hyperemia used to be called “fluxion,” a term now rarely used. _Active hyperemia_ means an increased supply of _arterial_ blood. In _passive hyperemia_ the oversupply is rather of _venous_ blood. In the former case the condition seems due to overactivity of the heart, with such local tissue changes as permit it to occur. In passive hyperemia the blood current is slower--there is a tendency toward, and sometimes an actual, stagnation; all of which is usually due to obstruction of the return of blood to the heart. The conditions permitting these two results may be widely variant.

=Active Hyperemia.=--Active hyperemia may be produced by purely nervous influences, even those of emotional origin. The flushing of the face which is known as “blushing” is, perhaps, the most common illustration of this fact. It is well known also that this is, in some degree at least, the result of division of certain nerves which have to do with the regulation of the blood supply. The cervical sympathetic is the best known and most often studied of these, and the consequences of division of this nerve in the neck are stated in all the text-books on physiology. So also by electrical stimulation of certain nerves the parts supplied by them can be made to show a very

## active hyperemia, which will subside shortly after discontinuance of

stimulation, providing this has not been kept up too long. In active hyperemia there is absolute increase of intra-arterial tension, and under these circumstances pulsation may be noted in those small vessels in which commonly it is not seen nor felt. This is the explanation of the throbbing pain complained of under many actively hyperemic conditions. This hyperemia affords the explanation of the clinical signs to which attention has already been called. The increased heat of the part is the result of greater access of blood, which prevents cooling by radiation and evaporation; the peculiar redness is due to the greater filling of the capillaries with the blood, which gives the peculiar hue to the skin and visible textures; while to the increased pressure upon sensory nerves is also due the pain. The minuter changes occurring within the congested part call for more accurate description. Whether or not there is actual dilatation of capillaries under these circumstances is a matter still under dispute, but of the dilatation of the larger vessels there can be no possible question.

As hyperemia is to such a great extent brought about by action of the nervous system, it is well to divide it more accurately into the hyperemia of paralysis, or _neuroparalytic congestion_, which is the result of a paralysis of the constrictor fibers of the vasomotor system, and into the hyperemia of irritation, or _neurotonic congestion_, which is due to the irritation of the dilators (Recklinghausen). Physiologists are fairly well agreed that as between the dilating and the constricting apparatus of the vasomotor system there is ordinarily preserved a certain degree of equilibrium; to which fact is probably due that normal condition of affairs inaugurated after temporary disturbance, since overaction in one direction succeeds reaction in the other. As Warren has illustrated this, our common treatment of frostbite by cold applications is a concession to this fact, since by the cold applications we endeavor to limit the reaction which would otherwise follow after thawing out the frozen part.

The best examples of the _hyperemia of paralysis_ are perhaps to be met with after certain injuries to nerves, as, for instance, flushing of the face and hypersecretion of nasal mucus, tears, etc., after injury to the cervical sympathetic. Such, too, in its essentials is that form of shock known as brain concussion, which is often followed by nutritive disturbances among the brain cells, with consequent perversion of brain function.

Waller’s experiment of placing a freezing mixture over the ulnar nerve at the back of the elbow is also significant, the result being congestion and elevation of surface temperature of the fingers supplied by this nerve. Congestion and swelling have also been observed after fracture of the internal condyle of the humerus, by which this nerve was pressed upon; and similar phenomena may be noted in fingers or toes as the result of injuries of other nerves.

Hyperemia due to _paralysis of the perivascular ganglia_ is observed sometimes in transplanted flaps, in the suffusion of a limb after removal of the Esmarch bandage, in the congestion of certain sac walls after tapping, in the hyperemia of, perhaps even hemorrhage from, the bladder wall after too quickly relieving its overdistention, and in the swelling of the extremities when they begin to be first used after having been put at rest because of injury.

The _hyperemias of dilatation_ are more acute in course and manifestation. Along with them go sharp pain, hypersecretion of glands, edema, and sometimes desquamation of superficial parts. The facial blush due to effusion; the temporary flushing due to indulgence in alcohol; the suffusion of the conjunctiva, perhaps the face, with hyperlacrymation, accompanying facial neuralgia or hemicrania; and the hyperemia consequent upon herpes zoster, urticaria, etc., are illustrative examples of this form. The erythema due to nerve irritation or injury, the swelling of the joints which appears after similar lesions, and that condition described by Mitchell as _erythromelalgia_, probably also belong here. In fact, almost all the reflex hyperemias are hyperemias of dilatation.

The forms of hyperemia considered above belong mainly to the designation of _active_.

=Passive Hyperemia.=--Passive hyperemia is most often a mechanical consequence of obstruction of the return of blood, which can be imitated at will, and which is not infrequently the result of carelessness, as when an injured limb is bandaged too tightly. Experiment shows that when such mechanical obstruction has taken place there is temporary increase of intravenous pressure, which soon returns to the normal standard, such readjustment meaning that blood has found its way back by collateral circulation. Only when such rearrangement is possible do we have anything like permanent passive hyperemia. In organs with a single vein, such as the kidneys, the question of obstruction may assume a very important aspect. Under these circumstances the appearance of the involved part, when visible, is spoken of as _cyanotic_, while its surface, instead of being abnormally warm, is the reverse, due to impeded access of warm blood and more rapid surface cooling. The blood under such conditions is often darker than natural, because, remaining longer in the part, it absorbs more carbonic dioxide, or at least gives up more of its oxygen. As long as actual gangrene is not threatened, the blood column has a communicated pulsation, at least in the large veins. Escape of corpuscular elements may occur after the phenomena above noted have been present for some time; but the corpuscles rarely, if ever, escape until there has been more or less copious transudation of the fluid portion of the blood--_i. e._, the serum. When anatomical changes can be grossly, yet carefully, observed, as in the fundus of the eye, it is seen that under these circumstances the arteries become smaller, although whether this is a primary or secondary change is not to be determined. Discoloration of the integument is the frequent result of leakage of blood corpuscles and their pigmentary substance into the tissues, and is consequently a frequent accompaniment of chronic passive edema. It is seen often in connection with varicose veins of the legs.

Another form of passive congestion or hyperemia is that due to enfeeblement of the heart’s action by serious injury or wasting disease. When under these circumstances the lung has become more or less infiltrated with fluid, with hemorrhagic extravasation, the condition is known as _hypostatic pneumonia_--a misnomer, nevertheless indicating a condition which is only too frequent in the aged and feeble.

RESULTS OF HYPEREMIA AND CONGESTION.

These may be--

1. Speedy subsidence of all hyperemic phenomena--resolution.

2. Acute swelling.

3. Chronic swelling.

4. Gangrene.

5. Nutritional changes--atrophy and hypertrophy.

1. =Resolution.=--The speedy subsidence of hyperemic phenomena is known as _resolution_--a term which has also been applied to the retrograde phenomena after a genuine inflammation. For present purposes it implies, first, the subsidence into inactivity of the exciting cause or its complete removal. This may include the passing of an emotion, the removal of an irritant, the loosening of a bandage, the resort to certain applications or to constringing or astringing measures by which the effect is counteracted. A particle of dust in the conjunctiva may within a few moments produce an active congestion of the conjunctival vessels, which, ordinarily scarcely visible, becomes prominent and easily noted. The removal of the offending substance permits a return to their original size in perhaps a half-hour. This is an example of the speedy subsidence of the hyperemia of dilatation after removal of the cause. Should the hyperemia not subside promptly, it is well to use cold applications, or in this instance an astringent collyrium, or some agent whose physiological effect it is to produce vascular contraction, as cocaine, adrenal extract, etc.

2. =Acute Swelling.=--When the effusion above referred to takes place into loose connective tissues the condition is spoken of technically as _edema_, while when it occurs into a previously existing cavity, such as that of a joint, it is known as an _effusion_. The amount of blood thus effused will be influenced by the anatomical and mechanical conditions existing about the part. It may be presumed, as a general rule, that when the extra vascular pressure equals the intravascular pressure little or no more fluid may escape. As a matter of fact, it is seldom that the former rises to the degree of the latter. Conversely, one method of treating such edemas and effusions is by some device which shall make the extravascular pressure exceed the intravascular, when the fluid is, as it were, forced back into the vessels, and is made to resume its proper place within the same. This is often done by taking advantage of elastic compression, as when a rubber bandage is applied about the part. In certain parts of the body it may be done by pressure brought about by some other device. Pressure may be used for two purposes:

_A._ To so increase extravascular pressure as to limit the possible amount of an effusion, as when it is put on early after an injury; or,

_B._ When it is used as a later resort for the purpose of reducing swelling which has already occurred.

3. =Chronic Swelling.=--This is something more than the swelling alluded to under _Acute Swelling_. Chronic swelling implies either a continuous passive hyperemia, or, what is more common, a positive increase in tissue elements as the result of an oversupply of nutrition brought by the blood, which itself was furnished to the part in a degree far in excess of its needs. The result is a more rapid reproduction of cell elements, with result in the shape of tissue thickenings or tissue enlargements, known as _hypertrophy_, or, more properly speaking, _hyperplasia_, of a part, and to the laity as “overgrowth.” This chronic swelling or chronic enlargement is in some degree also connected with the phenomena of escape of white corpuscles from the bloodvessels and mitotic division of certain tissue cells, which have up to this time been usually regarded as a feature of the true inflammatory process.

4. =Gangrene.=--This may be the result of hyperemia--for the most part the passive forms--though most instances of gangrene due to intrinsic causes are inseparable from the presence of infectious microörganisms. The gangrene which is spoken of here includes that due to the pressure of tumors, tight dressings, or any natural or intrinsic agency, and that due to pressure from without when not so pronounced as to produce immediate and total loss of circulation in a part. It includes the formation of many bed-sores and so-called _pressure-sores_, which may be due to an enfeebled heart, to an obstructed pulmonary circulation, or to external pressure in conjunction with cardiac debility. While insisting, then, that gangrene should be recognized as a possible result of hyperemia, it may be added that it is in effect a tissue death, and that dead tissue is always and everywhere practically the same thing, no matter by what causes brought about. Consequently, the subject of gangrene will be considered under a separate heading.

5. =Nutritional Changes= will be considered later.

_The consequence of persistent hyperemia is transudation_--i. e., _escape of blood plasm from the vessels into body cavities and tissue interspaces_. This leads to consideration under a distinct heading of--

TRANSUDATES AND EXUDATES.

Exudation may occur in vascular and non-vascular, in firm and soft tissues, in, under, and upon membranes. With respect to location, exudates are described as _free_, when found upon free surfaces or within natural cavities; _interstitial_, when found between the tissues or parts of tissues; and _parenchymatous_, when they are situated within the tissues themselves, particularly in epithelial and glandular cells of any kind.

Exudates are _serous_, _mucous_, _fibrinous_, or _mixed_, the mixed forms including the so-called _seropurulent_, the _mucopurulent_, the _croupous_, and the _diphtheritic_.

When any exudate contains red globules in sufficient quantity to stain it, it is called _hemorrhagic_.

Serous transudates from free surfaces are sometimes spoken of as serous _catarrhs_; when into cavities, as _dropsies_; when into tissues, as _edema_; when occurring beneath the epidermis they form _serous vesicles_ or _blebs_ or _bullæ_.

_Fibrinous_ exudation refers to the fluid which coagulates soon after its exit from the vessels within those spaces into which it has oozed. When flocculi of coagula float in serous fluid it is known as a _serofibrinous_ exudate. Pure fibrinous exudate occurs rarely, save in and upon mucous membranes. The extent to which exposure to the air is responsible for the firm coagulation of the fibrin previously held in solution is uncertain. The most potent factors in producing such coagulation are bacteria, but it is not yet disproved that coagulation may occur without their aid. When such coagulation occurs upon the surface of a mucous membrane it has been spoken of as _croupous_. When the epithelial covering as well as the basement membrane, and often the submucous tissues, are involved, so that the membrane cannot be stripped off without tearing across minute bloodvessels, the exudate has been known as _diphtheritic_. These terms may possibly be still retained in an adjective sense as implying the exact location of a surface exudate, but are scarcely to be used in any other significance.

The following table illustrates significant differences whose full importance cannot be impressed before a study of inflammation has been carefully entered upon:

_Hyperemic Transudates._ _Inflammatory Exudates._

Poor in albumin. Rich in albumin. Rarely coagulate in the tissues. Usually coagulate in the tissues. Contain few cells. Contain numerous cells. Low specific gravity. High specific gravity. Contain no peptone. Contain peptone (product of cell disintegration).

TREATMENT OF CONGESTION AND HYPEREMIA.

These disturbances are to be combated, first of all, by insisting upon _physiological rest_. This, perhaps, is the most important measure of all. The profession is indebted to Hilton for the decided advance which he made in the treatment of congestive and inflammatory affections by insisting upon this principle in his celebrated work on _Rest and Pain_, which every young practitioner should read. Aside from this first and underlying principle, the treatment must, in some measure at least, be based upon the time at which we are called upon to treat the case. If seen at once, before exudation has been excessive or the other disturbances marked, we may carry out a certain line of treatment for the purpose of limiting all these unpleasant features. On the other hand, if seen late, when exudation has been copious and when pain and other disturbances are due to its presence, a distinctly different course will be adopted.

Toward the end first mentioned--namely, the limitation of hyperemia--we may adopt local and general measures. Local measures include graduated pressure, providing this is not intolerable to the patient, so equalized that outside of the vessels it shall equal that inside. This may be done by careful bandaging, extreme care being taken that the pressure be applied from the very extremity of the limb; otherwise, passive exudation might be augmented and gangrene be precipitated. Elevation of a limb will often accomplish the same purpose. Cold, which is in effect an astringent and which tends to contract bloodvessels, is another measure in the same direction, and if applied early will do much to limit the degree of the attack. This may be applied as dry or moist cold, and should be gradually mitigated as the congestion subsides. It acts through the vasomotor system, and is a measure to be resorted to with caution. An efficient way of applying dry cold can be extemporized by a few yards of rubber tubing, held in place by wire or sewed in place to a piece of cloth, through which a stream of cold water is permitted to pass.

Heat is another efficient means, acting, however, in a rather different way. Heat is a measure to be employed to hasten the disappearance of exudation--in other words to quicken resorption, which it does by equalizing blood pressure, dilating the capillaries, stimulating the lymphatic current, and in every way helping to clear the tissues of that which has left the bloodvessels.

It is necessary also, at least in extreme cases, to employ some detergent or derivative measures, including _bloodletting_, to which we do not resort sufficiently often. When used for this purpose, depletion should be applied at the area involved, if possible. This may be done either as venesection, by leeching, either with the natural or the artificial leech, or by a series of minute punctures or incisions, which give relief to tension, permit the rapid escape of fluid exudate, and often save tissues from the disastrous effects of strangulation. In some cases of deep-seated congestions these measures are inapplicable, and venesection at the point of election--say the cephalic vein in the arm--may be followed by great benefit. Another method of depletion is by administration of cathartics, such intestinal activity being stimulated as shall lead to copious watery evacuations. The salines rank high as measures directed to this end, but in emergency much stronger and more drastic drugs may be administered, such as jalap, calomel, elaterium, etc. Diaphoretics and diuretics help to reduce temperature and in some degree to deplete, but their action is usually slow. When exudation is considerable in amount and confined to some one of the body cavities, it is often best combated, if at all obstinate, by the method of _aspiration_. This includes any suitable suction apparatus by which the fluid may be withdrawn through a small needle or cannula, the operation being trifling in difficulty, but one to be performed under strictest aseptic precautions, lest infection of an exudate already at hand be permitted.

Certain individuals, especially the neurotic, will need more or less anodyne, particularly when local applications fail to give relief. Sometimes a small dose of morphine administered hypodermically will

## act magically in making efficient those measures which would otherwise

be inefficient. In little children some anodyne or hypnotic will be of great service. Under all circumstances it is well to keep the lower bowel empty, and certain elderly individuals with weak and enfeebled hearts will need the stimulation to be afforded by digitalis, quinine, and alcohol, or preferably strychnine administered subcutaneously.

In cases of chronic hyperemia and its consequent hyperplasias (induration, thickening, etc.) there is no one measure so generally applicable and effective as the continued use of cold-water dressings. These are generally spoken of as “cold wet packs,” and may be continued--constantly or intermittently--for many days.

Massage is also an invaluable agent in the reduction of swelling and tissue overproduction. It promotes absorption, even of acute effusions, by equalizing the blood and hastening the lymph circulation, and under its scientific application it is surprising how firm exudates and old adhesions seem to disappear.

ATROPHY AND HYPERTROPHY, AND THE CONSEQUENCES OF ALTERED, DIMINISHED, AND PERVERTED NUTRITION.

As a consequence of increase of nutrition we have a condition known commonly as _hypertrophy_, more accurately as _hyperplasia_. Hypertrophy literally means overgrowth, whereas hyperplasia more accurately describes that which constitutes hypertrophy--namely, numerical increase of constituent cells. Common usage has made the more inaccurate name “hypertrophy” cover nearly all these conditions. _Hypertrophy_, or hyperplasia, _means enlargement of a part or of an organ beyond its usual limits_, and as the result of increased function or increased nutrition. It is to be distinguished from _gigantism_, which means inordinate enlargement as the result of a congenital tendency or condition. Hypertrophy is--

A. _Physiological_ {1. Compensatory; {2. From deficient use.

{3. Local; B. _Pathological_ {4. General; {5. Senile; {6. Congenital.

[Illustration: FIG. 1

Congenital hypertrophy: gigantism of both lower extremities. (Case of Dr. Graefe [Sandusky].)]

A. =Physiological Hypertrophy.=--1. This includes many of the compensatory enlargements of an organ or a part when extra work is put upon it, owing to deficiency of some other organ or part. This is spoken of as _compensatory_ enlargement. Illustrative examples may be seen in the heart, which becomes larger and stronger when the bloodvessel walls are diseased and their lumen narrowed, or when other obstructions to circulation are brought about; again, in enlargement of one kidney after extirpation of the other, or of the wall of the stomach when the pylorus is constricted or obstructed; again, of the fibula after weakening or more or less destruction of the tibia, or of the shaft of any bone when it has been weakened at some point by not too acute disease; or, again, of the walls of bursæ after constant friction.

2. The best examples of physiological hypertrophy owing to deficient use are perhaps seen in some of the lower animals; as, for instance, in the teeth of such rodents as beavers when kept in captivity and prevented from natural use.

B. =Pathological Hypertrophy.=--3, 4. Instances of this are everywhere and every day are met in the results of so-called _chronic inflammation_, a term which is a complete misnomer and should be expunged from text-book use. So-called chronic inflammation simply means increase of nutrition owing to a certain degree of hyperemia, which may have been produced in the first place as the result of traumatism, which may have come from chemical irritants circulating in the fluids of the part--as, for example, uric acid, etc.--or which is brought about as the result of perverted trophic-nerve influence. Instances of local pathological hypertrophy may be seen in the thickened periosteum after injury, in the enlargement of a phalanx known as the “baseball finger,” and in numerous other places; or they may be general, in which case they are brought about mainly by some irritating material in the general circulation. The unknown poison of syphilis generally provokes such nutritive disturbances.

5. _Senile hypertrophy_ is connected with nutritional disturbances characteristic of old age, as to whose remote causes we are still uncertain. Instances of senile hypertrophy, however, are common,

## particularly in the prostates of elderly men, which are liable to

undergo extensive enlargement.

6. Of _congenital_ hypertrophy and that of unknown origin we see, for instance, examples in certain rare cases of hypertrophy of the breast, in leontiasis, perhaps even in acromegaly, etc.; and these are to be distinguished from _gigantism_, because in most instances of the former type the hypertrophic tendency is not manifested until youth or adult life, whereas gigantism is a condition in which the tendency was apparent even before the birth of the individual.

ATROPHY.

_Atrophy implies impaired nutrition, and means diminution in the size of an organ or part_, and is the converse of hypertrophy. It is necessary to make plain that in atrophy nutrition is only impaired and not arrested, since complete arrest of nutrition means necrosis--_i. e._, gangrene or disappearance of parts. It may be--

{1. From disuse without disease; A. _Physiological_ {2. Biological or developmental; {3. Senile.

{4. Result of acute tissue losses; B. _Pathological_ {5. Result of phagocytic activity; {6. Result of continuous pressure; {7. Specific.

A. =Physiological Atrophy.=--1. This is always the result of disuse or impaired function from any cause. Its evidences are generally seen in the fatty structures and muscles--_i. e._, in the soft parts. It is true, however, even of the bones, or, of greater interest, even in the brain cells. We see evidences of it also in minute organs; as, for example, in the digestive glands in certain cases where diet is restricted. Again, we see it in the diminution of the size of the heart after hip amputation, less being required of that organ, and also in the entire structure of the rectum after colostomy.

2. Examples of the _developmental type_ are best seen in the natural disappearance of the hypogastric arteries, the ductus arteriosus, the vitelline duct, the Wolffian bodies, and in the various generative ducts (Gärtner’s, etc.) shortly after the birth of the human individual. We sometimes see it also in the prostate after orchidectomy. Equally illustrative is the disappearance of the tail and gills of the tadpole, the eyes of animals living in caverns, and, in a general way, of organs which become useless owing to a different environment.

3. _Senile_ atrophy is seen equally well in the hair follicles, the teeth, the bones, and the sexual organs of elderly people--in fact, in all their tissues, even in the brain.

B. =Pathological Atrophy.=--4. Acute atrophy of surrounding tissues is the necessary accompaniment of destruction by suppurative or other disturbances; that is, parts disappear by absorption which have not been interfered with by pyogenic organisms. So complete may atrophy occur under these circumstances as to cause disablement of an organ or part. This kind of senile disappearance is merely an expression of phagocytic activity, although not now a question of bacteria.

5. The same is true of that variety spoken of above as _biological_ or _developmental_, since phagocytes are the active agents in producing the disappearance of the tadpole’s tail.

6. A more slow form of pathological atrophy is seen in the _gradual disappearance_ of tissues in the neighborhood of advancing tumors, enlarging cysts, etc. This is perhaps but another expression of atrophy from continuous pressure. But a still better illustration is the atrophy which comes from immobilization of a part without pressure. This is usually the case when splints or orthopedic apparatus have to be kept in place for some time.

7. _Specific_ forms of pathological atrophy are largely connected with disturbances in the central nervous system. They are often referred to as _trophoneurotic_. Their exact mechanism is not yet understood, and cases may be confused under this head whose remote causes are widely different. Here should be included, for instance, the atrophy of a deep bone which occurs after extensive burn of the surface; also that peculiar form of atrophy of tissues in the stump which produces the so-called _conical stump_. These cases are of a more complicated character, for if pressure is removed from the bone end, especially in young people, the bone tends to grow faster than it should, while the soft parts disappear, partly as the result of mere disuse or loss of function. In this way conicity is produced, which sometimes calls for subsequent re-amputation. Under this head might also be included the so-called “trophic inflammation” (misnomer) of some writers, such, for example, as ulceration of the cornea after division of the trigeminus. The general subject of _atrophic elongation_ also belongs here, referring to the fact that as a result of disuse, or sometimes of active disease, the bones, while showing atrophic changes in other respects, actually increase in length. Should such increase occur in one bone of those portions of the limbs which are supplied with two, the result would be posture deformity and displacement of the terminal portion.

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