436 



INDEX 



internal, 154; of liver, 145, 153; mode 

 of discharge, 153; mucous, 153; oily, 

 153; origin of, 153; of pancreas, 153, 

 159; performed by cytoplasm, 153; 

 of salivary glands, 143; of sexual 

 glands, 154; of small intestine, 145; 

 of thymus, 154; of thyroid, 154 



Secretions, 59; acids, 154; effects of, 144, 

 146, 153, 154, 159; electric current, 

 155; gas, 154; of glands, 112; causing 

 light, 155; milk, 154; odors, 154; 

 poisons, 154; sebaceous materials, 

 154; sepia, 154; silk, 154; wax, 154 



Secretory cells, 110 



Sections, in taxonomy, 264 



Segmentation, 187, 217 



Segments, 108 



Segregation, 242, 249, 254; of genes, 244 



Selachii, classified, 270 



Selection, natural, 359; sexual, 359 



Self fertilization, 186, 191 



Semicircular canals, 230, 349 



Seminal receptacle, 128, 129, 130, 185; 

 of earthworm, 119 



Seminal vesicle, 120, 128, 131; of earth- 

 worm, 119 



Semipermeable membrane, 44, 45, 46, 47 



Sensations, of various kinds, 163, 164 



Sense organs, special, 163 



Sensory cells, 162 



Sensory neurons, 160, 161 



Sepedon fuscipennis, 232 



Sepia, a glandular secretion, 154 



Septa, 108, 115, 331; of cephalopods, 330 



Septibranchia, classified, 269 



Series, mastodon-elephant, 319 



Serranus, 191; fertilization in, 191 



Seta and muscles in earthworm, figure of, 

 134 



Setae, 133; pivoting of, 135 



Severino, 17 



Sex, determination of, 239, 252, 253 



Sexes, congregation of, in various Sni- 

 mals, 192 



Sex-linkage, 254 



Sexual glands, secretions of, 154 



Sexual impulse in society formation, 278 



Sexual organs, growth of influenced by 

 secretions, 154; in lizard, 195; in 

 Polygyra albolabris, 191 



Sexual reproduction, 90, 168, 173, 186; 

 extent of, 173; in metazoa, 174; in 

 Protozoa, 175 



Sexual selection, 342, 359 



Sexual system, 114; function of, 127-130; 

 structure of, 127-130 



Sharks, classified, 273; embryos of, 197; 

 place of development of eggs, 196; 

 placenta of, 197 



Sheldrake, sperm of, 216 



Shivering, a reflex action, 161 



Shrimps, 173; classified, 273 



Siagonodon humilis, range of, 309 



Siberia, mammoths in, 310, 311 



Silica, 32 



Silk, a glandular secretion, 154 



Silurian, 332; in time scale, 315 



Simple multicellular gland. 111 



Single comb, 362 



Siphonaptera, classified, 270 



Siphonophora, 98; budding in, 168; 

 classified, 269 



Siphonophore, 98; budding in, 169 



Sirenia, classified, 271 



Skates, classified, 273 



Skein, close, 71; 'oose, 72 



Skeleton, appendicular, 135, 137; axial, 

 135; growth of, influenced by secre- 

 tions, 154; of vertebrates, 135 



Skin, in excretion, 150, 151; nerve endings 

 of, 163; in respiration, 147; roughen- 

 ing of, 161 



Skink, disposition of eggs, 199, 200. (See 

 also Leiolopisma.) 



Skull, 135; evolution of, in horse series, 

 324; of Eohippus, 326; of Merychip- 

 pus, 327; of Mesohippus, 326 



Slavery, 275, 277, 280; in ants, 280; in 

 plant lice, 280 



Slime-molds, colonies of, 278 



Slime tube, 184, 185 



Sloth, figure of, frontispiece; habitat of, 

 281 



Small intestine, 117, 120; digestion in 

 (see Digestion); mucosa of, 146; 

 secretion of, 145 



Smell, 164 



Smooth coats in guinea-pigs, 247-250 



Smooth muscle, 112 



Snails, 107, 173; classified, 273; copula- 

 tory habits of, 193; egg case of, 198; 

 fertilization in, 194; hermaphrodi- 

 tism in, 190 



Snakes, classified, 274; congregation of, 

 278; development of eggs, 195 



Snow shoe rabbit, range of, 292 



