CONTENTS. 



Page 



Introduction 197 



Historical 198 



Methods 205 



Observations 206 



Adult spermatozoa 206 



Observations upon the living cells of the testis 210 



Growth of the apyrene spermatoblast 212 



Growth and differentiation of the apyrene spermatosome 221 



Discussion 229 



Summary 235 



Bibliography 236 



Explanation of figures 238 



196 



