viii TABLE OF CONTENTS 



PAGES 



frequent breeding on the sperm-cells, 46 ; Vitality of 

 spermatozoa within the female generative organs, 47 ; 

 Effect of intoxication of the male parent on his off- 

 spring, 48 ; Effect of lead poisoning on the male germ- 

 cells as indicated by the offspring, 49. 



CHAPTER III 



THE BREEDING SEASON 52-65 



Changed conditions, 60 ; Phases of the breeding sea- 

 son, 51 ; Procestram, 52 ; CEstrum, 53 ; Metoestrum, 54 ; 

 Dicestrum, 55 ; Puberty, 56 ; Conditions influencing 

 puberty, 57 ; The O3strnm and lactation, 58 ; Heat dur- 

 ing pregnancy, 59 ; Superfcetation, 60 ; Examples of 

 superfoetation, 61 ; Recurrence and duration of the 

 oestrum, 62 ; Effect of ration on recurrence of oestrum, 63. 



CHAPTER IV 

 GESTATION AND LACTATION ....... 66-84 



Gestation : Indications of pregnancy, 64 ; Physical 

 examination for pregnancy, 65 ; The period of gestation, 

 66 ; Causes of variation in length of gestation period, 67 ; 

 Incubation, 68 ; Parturition, 69 ; Normal parturition of 

 the domestic animals, 70 ; Mai-presentations, 71 ; Normal 

 presentations, 72 ; Treatment for mal-presentation, 73. 



Lactation : The mammary glands, 74 ; The duration 

 of lactation, 75 ; The food supply, 76 ; Habit, 77 ; He- 

 redity, 78 ; Exercise, 79 ; Climate, 80 ; Unusual lacta- 

 tion, 81. 



CHAPTER V 



FERTILITY 85-112 



The number of young at a birth, 82 ; Period of gesta- 

 tion and fertility, 83 ; Fertility and the frequency of the 

 recurrence of the oestrum, 84 ; Fertility and gestation, 85 ; 

 Duration of the reproductive period, 86; Confinement 

 and fertility, 87 ; The fertility of domesticated animals, 

 88 ; Age and fertility, 89 ; Relation of age to fertility in 



