INDEX 



437 



Soaps, 145 



Societies, 102 



Society formation, 275, 277, 27S; in- 

 sects, 278; sexual impulse in, 278 



Soil, an environmental factor, 283, 305 



Solanin, 187 



Solanum rostratum, food of Leptinotarsa 

 (see Leptinotarsa) 



Sole, 107 



Solifugae, classified, 270 



Soluble wastes, excretion of, 152 



Solute, 44 



Solutions, 44 



Solvent, 44 



Somatic cells, 86, 90, 91, 169, 206, 208, 

 236, 237, 238 



Somites, 108 



Sound, 164 



South America, severance from North 

 America, 318 



Spallanzani, 166 



Sparrow, grasshopper, range of, 292 



Specialization, 91, 92 



Species, 16; changeability of, 340; fixitj^ 

 of, 340; mutability of, 22; range of, 

 290, 291 ; relations of, in associations, 

 277, 281 ; in taxonomy, 262, 263, 264 



Sperm, 174, 185; head of, 215; mid-piece 

 of, 216; role in fertilization, 187- 

 188; tail of, 216 



Spermaducal pores, 184 



Spermaries, 128 



Spermatid, 211, 212, 253 



Spermatocytes, primary, 210, 211; sec- 

 ondary, 211, 212 



Spermatogenesis, 209, 210-212 



Spermatogonia, 209, 210, 211 



Spermatogonium, 209 



Spermatophore, 184, 192, 193 



Spermatozoa, 14, 129, 174, 177, 211, 

 216; form of, 215-216; path of, 131 



Spermatozoon, 174, 175, 212 



Sperm cells, 174 



Spermophile, Franklin's, range of, 292; 

 thirteen-lined, range of, 292 



Sphenisciformes, classified, 271 



Spherical aberration, 15 



Spheroid colony, 85, 87-90 



Spicule, 65, 170; amphidisc, 170 



Spiders, 173; classified, 273; egg case of, 

 198, 200 



Spinal cord, 114, 116, 120, 141, 160, 161, 

 210, 225, 227, 228; function of, 162 



Spinal nerves, 229, 230; origin of, by two 



roots, 142; roots of, 229 

 Spindle, 72, 73, 74, 70, 175; origin of, in 



mitosis, 76 

 Spindle fibers, 73, 75; as protoplasmic 



threads, 79 

 Spines, 133 

 Spiracles, 121 



Spireme, 75, 77; close, 71; loose, 72 

 Spleen, 120 

 Splint bones, 327, 328 

 Sponges, 94, 169, 170; birth stages in, 202; 



budding in, 168; classified, 272; 



hermaphroditism in, 190 

 Spontaneous generation, 165, 166; modern 



idea of, 167-168 

 Spore formation, in gregarines, 178 

 Sporocyst, 182, 183 

 Sporophyte, 253 

 Sporosac, of Hydractinia, 97 

 Sporozoa, 172, 176, 180; classified, 268, 



271 

 Sporozoites, 172, 177, 178 

 Sporulation, 172, 186 

 Spotted sandpiper, birth stage in, 203 

 Spruce grouse, range of, 292 

 SquaU, classified, ^70 

 Squamata, classified, 271 

 Squamous epithelium, 109, 110 

 Squids, 173 



Starch, digestion of, 143, 144, 145, 146 

 Starfish, 106, 172, 187; birth stage in, 



202; classified, 272; fertiUzation in, 



192; parental care in, 198 

 Statoblasts, 171; of Cnstatella mucedo, 



170 

 Stauromedusse, classified, 269 

 Steapsin, 145 

 Stearic acid, 52 

 Stegocephali, 331 

 Stegodon, 320, 321, 322 

 Stegosaurus, 332, 334 

 Stentor, 31, 66, 68, 85; regeneration in, 



67 

 Sternum, 135 

 Stimuli, 65 

 Stolon, 103, 169 

 Stolonifera, classified, 269 

 Stomach, 95, 117, 120, 225, 228; diges- 

 tion in, 144 

 Stomatopoda, classified, 270 

 Strain sensation, 163 

 Stratified epitheUum, 110 



