Fig. 425. Diagram illustrative of the internal anatomy of the leech.

a. Brain. b. Last ganglion. Between these will be observed the chain of ganglia of which they form portions. c. Lateral or branchial vessels. d. Folded mucous glands; each is connected by a duct to an air-vesicle. e. Penis, the rounded enlarged base of which is supposed to contain the prostate gland. f. Vesiculae seminales. g. Vasa deferentia. h. Testicles. i. Uterus. k. Ovaries.

This image is from _ in Pereira's Elements of Materia Medica and Therapeutics, 1854.