54 



SEX AND HEREDITY 



the reproductive process in the Animal Kingdom, and in 

 these two lectures I propose to deal with some of the 



general principles which have 

 ( been elucidated, leaving on 



one side the phenomena of 

 Heredity, which will be ex- 

 pounded to you later by a 

 distinguished investigator of 

 this subject. 



The essential features of 

 the reproductive process are 

 most easily grasped by study- 

 ing it in the lowest and simp- 

 lest animals forming the group 

 Protozoa animals of minute 

 size, in which the individual 

 consists of a single cell which 

 creeps, or swims, or floats, 

 leading an independent exist- 

 ence. We will commence with 

 Copromonas, a creature which 

 occurs not uncommonly in 

 water in which Frogs are 

 kept. The creature consists 

 of a minute pear-shaped cell, 

 i.e. a mass of protoplasm con- 

 taining a nucleus (Fig. 32, N). 

 The outer layer of protoplasm 

 is slightly stiffened, forming a 

 thin skin or pellicle which 

 keeps the creature in its 

 definite shape. Projecting from the narrower end is 

 a long very thin thread of protoplasm the flagellum 



c v. 



--AT 



FIG. 32. 



Copromonas, as seen under a very high 

 magnification (after Dobell). c.v, contrac- 

 tile vacuole ; /, flagellum ; f.v, food vacuole 

 (temporary stomach) ; N, nucleus ; r, 

 reservoir. 



