INDEX 



309 



Primary sexual characters, 19. 

 Prophase in cell division, 8. 

 Protein, effect of, on foetus, 266. 

 Protoplasm, 1, 2, 4. 

 Puberty, 56. 



conditions influencing, 58. 

 Pure lines, 146, 291. 



Vilmorin's wheat-breeding, 292. 



Ram, age influences fertility, 94. 

 Recurrence of oestrum, 63. 

 Reduction, 37. 



chromosomes, 37. 



in the female, 40. 



in the male, 41. 



Registered breeding animals, 296. 

 Registry associations, 297. 

 Reproduction, 16, 183. 

 Reproductive organs, of the female, 

 24. 



of the male, 19. 



Retarded growth, caused by pre- 

 mature breeding, 274. 



permanent effect of, 268. 

 Ritzema Bos, 232. 

 Rommel, 92. 

 Roux, 38, 39. 



Secondary sexual characters, 19, 185. 

 Selecting the best, 300. 

 Selection, 284. 

 aids to, 288. 

 importance in animal-breeding, 



286. 



methodical, 286. 

 natural, 285. 

 Sex, 183. 



effect of age on determination of, 



189. 



effect of nutrition on, 191. 

 influenced by maturity of ovum, 



192. 



not controlled by external condi- 

 tions, 194. 

 proportion influenced by season, 



193. 



Sex-linked characters, 188. 

 Sexual glands, transplantation of, 



187. 

 reproduction, 17. 



Sheep, fertility influenced by age, 



93. 



Size, decreased by premature breed- 

 ing, 272. 



improvement in, 280. 



of litter influenced by age, 91. 

 Somato plasm, 161. 

 Sow, genital organs of, 30. 



size of litter influenced by age, 



91. 



Spallanzani, 43. 

 Spaying, 23. 

 Spencer, 71, 133, 167. 

 Spermato genesis, 41. 

 Spermatozoa, 14. 



vitality within female generative 



organs, 46. 



Spermatozoon in fertilization, 37. 

 Sperm-cells, conditions influencing 

 vitality, 44. 



weakened by too frequent breed- 

 ing, 45. 



Steenbock, 64, 266. 

 Sterility, 113. 



abortion, 120, 123. 



causes, 114, 119. 



closure of cervix, 117. 



excessive food supply, 99. 



fatty degeneration, 120. 



in the female, 117. 



in the male, 114. 



obstruction in Fallopian tube, 

 118. 



twin births (free-martin), 129. 

 Stockard, 50. 

 Superfoetation, 60. 



examples of, 61. 



Tanner, 104, 116. 

 Taylor, 126. 

 Telegony, 166. 



possible appearance in mule 



breeding, 170. 



Telophase in cell division, 12. 

 Tessier, 70, 72. 

 Testicles, 20. 



Theory of pure lines, 146. 

 Thomson, 133. 

 Thornton, 59. 

 Thury, 192. 



