64 



INDEX 



Scurvy, caused by absence of vita- 

 mines, 139 



Sea anemone, 3 



Sea-urchin, artificial fertilisation in, 

 10 



Seasons of sexual activity, 12, 13, 41 



Sebaceous glands, 24, 34, 83, 85 



Secondary sex characters, 59, 86-91, 

 93, 113, 126, 134; effect of 

 castration on, 87-90, 94-5 



Secretions, beneficial effect on 

 opposite sex, 24, 40 



Secretory tubule, 21 



Segmentation, 10 



Segmentation cavity, 61 



Segmentation nucleus, 9 



Selective action of placenta, 132 



Self -fertilisation, 11 



Sellheim, 28-9, 52-5 



Semen, 20, 21, 38, 40, 59 ; artificial 

 injection, 143 



Seminiferous duct, 16 



Seminiferous tubules, 18, 112, 127 



Semper, 13 



Senility after castration, 88 



Sense organs, 69 



Sensory nerves, 38 



Sensory end organs, 23, 32 



Septicpemia, 81-2 



Septum, 22 



Sertoli's cells, 19 



Sex, 3 ; and heredity, 115 ff. 



Sex cells, differentiation of, 6 



Sex chromosomes, see Chromosomes 



Sex-determination, 11, 36, 111, 118, 

 119, 123, 132-3, 136 ; theories on, 

 136 



Sex enzymes, 133 



Sex glands, 130, 135 



Sex ratios, 129 



Sex reversal, 124, 127-9, 135 ; 

 experimental, 130 



Sexes, numerical equality of, 126 



Sex-hnked characters, 118-9 



Sexton, 129 



Sexual aberrations, 144 



Sexual activity, seasons of, 12, 57 ; 

 cessation of, 59 



Sexual characters, change of, 127 ; 



of male latent in female and 



vice versa, 124 

 Sexual characters, secondary, 59, 



86-91, 93-5, 113, 126, 130, 134 

 Sexual cycle, mammalian, 41-59 

 Sexual desire, after castration, 



88 

 Sexual energy, sublimation of, 



148 

 Sexual glands, after castration, 



88 

 Sexual intercourse, 41, 144 ; differ- 

 ent sires, 142 

 Sexual maturity in animals, 59 

 Sexual organs, 16 ; male, 16 ff. ; 



female, 25 ff. ; connection of 



thyroid gland, 110 

 Sexual reflexes, 130 

 Sexual reproduction, 3, 4 ; in 



multicellular animals, 6 

 Sexual rhythm, 13 

 Sexual season, 41, 55, 56 

 Sexual selection, 126 

 Shark, Japanese, ova in, 8 

 Shattock and Seligman, 92 

 Sheep, 45, 49, 59, 89, 128, 142 ; 



pelvis in castrated, 94 ; uterus 



in, 30, 48 ; see also Ewe 

 Shipley and MacBride, 2, 4 

 Shorthorns, 140 

 Siegel, 56, 75 

 Simpson, Sir J. Y., 80 

 Sinus, 24, 72 

 Siskins, 122 

 Skeleton, 3 

 Skeleton muscles, 69 

 Skin, 2 ; in pregnancy, 75 

 Skin glands, 69 

 Skopecs, castration in, 87 

 Slipper animalcule, 5 

 Smelt, 14 



Smith and Potts, 129 

 SoBOTTA, 9, 29, 43 

 Sodium, in milk, 83 

 Somatopleur, 62-3, 66 

 Song in birds, in sexual selection, 

 126 



