INDEX 



423 



Series, in paleontology, 329 



Serum, 130 



Seta, in earthworm, 89 



Sex, inheritance of, 233, 234 



Sex-linkage, 234, 235, 236 



Sexual reproduction, 159-168 



Shark, 276 



Shell, egg, 200 



Shrimp, biogenetic law in, 256 



Silurian, 330, 335 



Simple gland, 84, 85 



Sinus node, 128 



Siphonophore, 174, 175, 263 



Skate, 277 



Skeleton, 87-93 



Skin, excretion by, 138 



Skink, care of eggs by, 187 



Skull, 90 



Slime tube, of earthworm, 167 



Snail, 271 



fossil, 331 



reproductive system of, 180 

 Socrates, 4 



Sodium chloride crystal, 35 

 Soil, ecological relations of, 304, 305 

 Soma, origin of, 70, 71 

 Somatic cells, origin of, 202, 205 

 Somite, 79 

 Species, 245, 248 



intersterility of, 353 



nature of, 352, 353 

 Spermatids, 194, 195 

 Spermatocytes, 193, 194, 195 



primary, 193, 194 



secondary, 194, 195 

 Spermatogenesis, 193, 194, 195, 198 

 Spermatogonium, 59, 193, 194 

 Spermatophore, 181 

 Spermatozoa, 160, 194, 196 



in Hydra, 72 

 Spheroid colony, 68, 69 

 Spicules, 87, 261 

 Spider, 273 

 Spinal cord, 141, 146 



in embryo, 205, 210, 211, 212 

 Spinal nerves, 143, 212, 213 

 Spindle, 56, 57, 60, 61 



location of, 61 

 Sponges, 88, 261, 262 



collared cells in, 52 



Sponges, reproduction of, 170 



spicules in, 87 

 Spongin, 261 



Spontaneous generation, 159 

 Sporozoa, 260 

 Sporulation, 170 

 Squamous epithelium, 84 

 Squid, 271 

 Starfish, 267, 268 

 Statoblast, of Bryozoa, 171 

 Steapsin, 105 

 Stegodon, 336, 337 

 Stegosaurus, 334 

 Sternum, 90 



Stimuli, responses to, 52, 53 

 Stomach, 101 



in embryo, 210, 212 



of frog, 102, 103 



of man, 103 

 Stratified epithelium, 84 

 Streams, 299, 300 

 Subclass, 247, 248 

 Subepithelial cells, in Hydra, 72 

 Subfamily, 247, 248, 250 

 Subgenus, 247, 248 

 Suborder, 247, 248 

 Subphylum, 247, 248 

 Subspecies, 247, 248 

 Succession, ecological, 291-293 



in peat bed, 292 

 Suctoria, 261 



Surface phenomena, 44, 45 

 Sustentative tissue, 81 

 Sutures, of cephalopod, 343 

 Swammerdam, Jan, 11 

 Sweat gland, 138 

 Sylvius, 8 



Symbiosis, 287, 288 

 Symmetry, 77, 78, 79 

 Sympathin, 148 

 Synapse, 28, 145, 150, 151 

 Synapta, larva of, 191 

 Syncytium, 66 

 Synonym, 249 

 System, 85 



in paleontology, 329 

 "Systema Naturae," 12, 245, 249 

 Systematic botany, 244-247 

 Systematic zoology, 244-247 

 Systemic circulation, 124 



