890 Ijidex 



Spectrum, 757, 757* 



Spemann, 581 



Spencer, 31 



Sperm, 119, 133,* 136, 136,* 137,* 

 138,* 138, 143, 154, 161-164, 

 163,* 186, 189, 194, 195, 201- 

 204, 286,* 320, 361,* 363, 

 365,* 372, 374,* 391, 398, 

 406, 450,* 514, 708* 

 mother cell, 277* 

 nucleus, 206 



Spermatheca, 325,* 391, 398, 406 

 Spermatid, 709, 710* 

 Spermatium, 163* 

 Spermatocyte, 709, 710* 

 Spermatogenesis, 708-710 

 Spermatogonia, 514, 675,* 709, 710* 

 Spermatozoa {see Sperm) 

 Spermogonium, 181 



Sphagnum (moss), 133, 134,* 187, 256 

 Sphenopsida, 110, 135, 191, 194 

 Spicule, 281,* 282* 

 Spider, 319, 325,* 326,* 543, 544, 

 544,* 547 



Spinal cord, 54, 55,* 328,* 332,* 340,* 

 436,* 437, 449,* 462,* 466, 

 496,* 502, 505 

 nerves, 54, 55,* 436,* 437, 502 

 Spindle, 63,* 64, 65, 66,* 67 

 cell, 434 

 muscle, 505 

 Spine, 300,* 303, 303,* 304 

 Spinneret, 325* 



Spiracle, 394,* 396,* 397, 403,* 448 

 Spirogyra (green alga), 115,* 116, 154, 

 157, 158* 



Spittle insect {see Insects] 



Splanchnic layer, 858 



Spleen, 332,* 427,* 507* 



Split protein, 772 



Sponges, 279-286, 281*-284,* 535, 536 



{see also Scypha; Leucoso- 



lenia; etc.) 



Spongilla (sponge), 284,* 286 

 Spongin, 280, 281 

 Spongocoel, 284* 

 Spontaneous generation, 732 

 Sporangiophore, 112, 119, 124,* 125, 

 136, 173 



Sporangium, 112, 119, 123,* 124,* 125, 

 130, 131,* 133,* 135, 135,* 

 136, 136,* 137, 150, 154, 165, 

 172, 173, 187-190, 192-195 



Spore, 112, 119-129, 172, 186-190, 192 

 mother cell, 132,* 187, 197 

 swarm, 156, 174 



Sporocyst, 275, 277,* 375,* 376, 787* 



Sporogony, 367 



Sporophore, 126,* 128,* 179, 192-195 

 Sporophyll, 135, 135,* 136,* 138, 192, 



196, 200-204 

 Sporophyte, 117, 128,* 130, 131,* 

 132,* 133-135, 136,* 137, 

 138, 138,* 140,* 143, 161, 

 164, 191-198, 200-204, 206, 

 207 



Sporozoa, 275, 363-367, 534* {see also 



Protozoa) 

 Sporozoite, 277,* 365,* 366, 367 

 Sporulation {see Spore) 

 Springtail, 411,* 550, 551* {see also 



Insects) 

 Squalus {see Sharks) 

 Squid, 311, 315,* 542 

 Staggers, 537, 661, 788 {see also Multi- 



ceps) 



Stalk, 190, 198, 223 



Stamen, 144,* 208-216, 223,* 224, 

 225* 



Staminate, 140,* 202-204 



Standard (of a flower), 212 



Stapes bone, 466, 498,* 505 



Starch, 115, 118, 153, 155, 162, 204 



Starfish, 300*-302,* 301, 540, 666 



Statocyst, 288* 



Statocyte, 284* 



Steapsin, 429, 476 



Stele, 145,* 214, 216, 220 



Stem, 133-148, 191-198, 200-205, 206- 



218, 222, 223, 223* 

 dicotyledonous, 143 

 monocotyledonous, 143 

 Stemonitis (slime mold), 123,* 173 

 Stentor {see Protozoa) 

 Sterigma (sterigmata) , 128,* 178,* 179 

 Sternum, 424, 462,* 466 

 Stigma, 143, 145,* 207-217, 223,* 225, 



225,* 276,* 358,* 359, 361,* 



363, 763 



Stimulus, 100, 106, 348, 494 



Sting, 404,* 406 



Stipe, 161 



Stirrup bone, 466, 498,* 505 



Stolon, 173 



Stoma (stomata), 56, 57,* 58,* 133, 

 141,* 145,* 147,* 189, 191, 

 192, 210, 211, 215, 224, 226 



Stomach, 299, 301,* 306,* 308,* 311*- 

 315,* 327,* 328,* 332,* 396,* 

 470,* 471,* 473, 507,* 509, 

 512 



Stomodeum, 290, 447 

 Stone cell (sclerenchyma) {see Tissues, 

 plant) 



fly {see Insects) 



lily, 304 



