47 



Fig. 4. Spermatozoa in various stages of develop- 

 ment : — 



a. Spermatozoon just set free, with long tail 



and readily-stained nucleolus. 



b. Spermatozoon in which the nucleolus has 



increased in size at the expense of the 

 granular protoplasm. 



c. Spermatozoon in which the whole of the 



"head is occupied by a clear, small, easily- 

 stained body, probably the altered 

 nucleolus. 

 d., e., f. Successive stages in the evolution of 

 the long, ribbon -like tail of the mature 

 spermatozoon, as shown in f. 



C. TINLINR AND CO., PRINTERS, VICTORI.\ STREET, LIVERPOOL. 



