Chapter XVI

).

Experimental studies of the physiological uses of lipoids have thus far been devoted almost exclusively to those of animal tissues. They have been seriously hampered by the difficulty of securing properly purified extracts of lecithin and similar lipoids. The same labile character which apparently makes them so important in the chemical changes in the cell makes them equally unstable compounds to work with in attempting to secure pure preparations for the purposes of experimental study. On this account, there is, as yet, no certain knowledge concerning their actual physiological uses. It is evident, however, that they have some really important rôle to play, which opens up a promising field for further study.

REFERENCES

ABDERHALDEN, E.--"Biochemisches Handlexikon, Band 3, Fette, Wachse, Phosphatide, Cerebroside, ..." 340 pages, Berlin, 1911.

HOPKINS, E.--"The Oil-Chemist's Handbook," 72 pages, New York, 1902.

LEATHES, J. B.--"The Fats," 138 pages, _Monographs_ on Biochemistry, London, 1913.

LEWKOWITSCH, J.--"Chemical Technology and Analysis of Oils, Fats, and Waxes," Vol. I, 542 pages, 54 figs.; Vol. II, 816 pages, 20 figs.; and Vol. III, 406 pages, 28 figs., London, 1909.

MACLEAN, H.--"Lecithin and Allied Substances," 206 pages, _Monographs_ on Biochemistry, London, 1913.

SOUTHCOMBE, J. E.--"Chemistry of the Oil Industries," 204 pages, 13 figs., London, 1918.

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