LIST OF ILLUSTRATIONS xi 



l-IG. PAGK 



41. Diagram showing a very early stage in the development 



op the human ovum ....... 64 



From " Gray's Anatomy^ 



42. Diagram showing the early formation of the allantois 05 



From " Gray's Anatomy." 



43. Diagram showing a later stage in the development of the 



allantois ......... 05 



From " Gray's Anatomy." 



44. Diagram showing the expansion of the amnion . . 65 



From " Gray's Anatomy." 



45. Diagram showing a later stage in the development of the 



umbilical cord ........ 65 



From " Gray's Anatomy." 



40. Human embryo, 2-6 mm. long ...... 66 



From " Gray's Anatomy." 



47. Human embryo, between eighteen and twenty-one days 



OLD 67 



From " Gray's Anatomy." 



48. Human embryo, between twenty-seven and thirty days 



OLD .......... 07 



From " Gray's Anatomy." 



49. Human embryo, between thirty-one and thirty-four days 



OLD .......... 68 



From " Gray's Anatomy." 



50. Human embryo, about six weeks old .... 68 



From " Gray's Anatomy." 



51. Human embryo, about eight and a half weeks old . . 69 



From " Gray'' s Anatomy." 



52. Section (semi- diagrammatic) through developing ovi^m 



embedded in the uterine decidua . . . .71 



From " Gray' s Anatomy." 



53. Diagram of chorionic villi into \\TiicH mesoderm has not 



yet grown ......... 72 



From " Grav' s Anatomv ." 



54. Section across a chorionic villus into which mesoderm 



has grown . 



From " Grav' s Anatomy 



73 



55. Normal birth . . . . " • • • • .79 



From Galabin's " Manual of Midwifery " (/. &= A. Churchill). 



50. Herdwick rari (normal) ....... 88 



From " fournal of Physiology" {Cambridge University Press). 



57. Herdwick wether (castrated young) . . . .88 



From " fournal of Physiology" {Cambridge University Press). 



58. Herdwick wether (castrated when four months old) . SO 



From " four nal of Physiology" {Cambridge University Press). 



50. Herdwick ram lamb from which one testis was removed 



four months after birth 



Frotn "\fournal of Physiology" {Cambridge Utiiversity Press). 



80 



