xiv ILLUSTRATIONS 



FIS. PAOE 



45. Section through follicle in late stage - 152 



46. Section through human testis and epididymis . 160 



47. Section through testis of monkey 161 



48. Section through portion of two seminiferous tubules in testis of rat 162 



49. A cell of Sertoli with which the spermatids are beginning to be connected 



(human) - - 163 



50. Diagram illustrating the cycle of phases in spermatogenesis 164 



51. Scheme of spermatogenesis and oogenesis 165 



52. Human spermatozoa on the flat and in profile 167 



53. Human spermatozoa - , . - 168 



54. Different forms of spermatozoa from different species of animals 169 



55. Diagram illustrating wave-like movement of swimming spermatozoon 171 



56. Successive stages in the fertilisation of an ovum of Echinus esculentus, 



showing the entrance of the spermatozoon . 181 



57. Three stages in the conjugation of male and female nucleus {Echinus) 182 



58. Fertilisation process in bat's ovum 183 



59. Chart showing amounts of oxygen taken up and carbon dioxide given off 



after the addition of sperm to the eggs of Echinus 192 



60. The insemination of the eggs of Saccocirrus - 1 93 



61. The entrance of the spermatozoon into the egg of Nereis ■ 195 



62. Passage of convoluted seminiferous tubules into straight tubules, etc. 240 



63. Transverse section through the tube of the epididymis 24] 



64. Transverse section through commencement of vas deferens 242 



65. Section through part of human prostate 247 



66. Section through prostate gland of monkey 249 



67. Transverse section through adult human penis 255 



68. Section through erectile tissue 256 



69. Part of transverse section through penis of monkey 257 



70. Distal end of ram's penis, showing glana and filiform appendage 259 



71. Transverse section through filiform appendage of ram 259 



72. Transverse section through middl^ of glans penis of ram . ^ 260 



73. Distal end of bull's penis, showing glans, etc. 261 



74. End-bulb in prostate - 269 



75. Diagram illustrating innervation of genital organs of male cat 271 



76. Herd wick ram (normal) - 323 



77. Herdwick wether (castrated young) 323 



78. Herdwick wether castrated when four months old 324 

 79.- Herdwick wether castrated when five months old 324 



80. Herdwick ram lamb with one testis removed 324 



81. Herdwick wether with epididymes retained - 324 



82. Successive stages in the regression of the comb of the cock after castration 335 



83. Ovariotomised brown Leghorn hen - 342 



84. Ovariotomised pullet with plumage and spurs of male 342 



85. Successive stages in the growth of the spurs of a hen after ovariotomy - 343 



86. Normal Rouen drake 344 



87. Normal Rouen duck 345 



88. Ovariotomised Rouen duck (Type I. ) 345 



89. Ovariotomised Rouen duck (Type II. ) 346 



90. Transverse section through rabbit's uterus after ovariotomy 349 



91. Transverse section through bitch's uterus 9J months after ovariotomy 349 



92. Section through ovary of rat after transplantation on to peritoneum '351 



93. Section through ovary of rat after transplantation on to peritoneum 352 



94. Transverse section through normal uterus of rat 353 



95. Transverse section through uterus of rat after ovariotomy - 354 



96. Transverse section through uterus of rat after ovarian transplantation 355 

 96a. Section through rat's kidney into the tissue of which an ovary had been 



triinsplanted 357 



