Chapter XV

).

[Illustration: Fig. 52.--Franz Leydig, 1821-1908 (April).

Courtesy of Dr. Wm. M. Wheeler.]

Leydig.--Franz Leydig (Fig. 52) was early in the field as a histologist with his handbook (_Lehrbuch der Histologie des Menschen und der Thiere_) published in 1857. He applied histology especially to the tissues of insects in 1864 and subsequent years, an account of which has already been given in