INDEX 



375 



Rhynchelmis, cleavage (radial), 236 

 Roux, 91, 265, 271, 284, 329 

 Ruckert, 75, 144 



Sachs-Hertwig, law of cleavage, 229 



Sala, 282 



Salamandra, mitosis, 46, 47; sper- 

 matogenesis, 124; spermatozoon, 

 100 



salts, effects upon development, 

 318, f. 



Sauropsids, gastrulation, 348, ff. 



Schaudinn, 191 



schizogonv, 4 



Schleichef, 44 



Schleiden, 31 



Schonfeld, 133 



Schultze, 31 



Schwann, 20, 31 



Schweigger-Seidel, 20 



Scott, 103 



ScyUium, egg membranes, 96 



sea-urchin, see Arbacia, Echinus, 

 Sphcer echinus, Strong ylocentrotus, 

 Toxopneustes. 



secondary sexual characters, in 

 Protozoa, 200 



Seeliger, 301 



segmentation (cleavage), 18 



segmentation cavity, 221, 331 



seminal fluid, 101 



seminal vesicles, 129 



senescence, 210 



Serranus, cleavage (discoid), 240; 

 primitive streak, 354 



Sertoli cells, 121 



sex, determination of, 306, ff., 315; 

 heredity of, 315; limited heredity, 

 316 



sexual and asexual reproduction, 12 



shells, of ova, 96 



Sida, spermatozoon, 99 



Silvestri, 315 



Sinety, 313 



skein, 45 



soma, 14 



spawning habits, 102, ff. 



sperm agonidia, 10 



spermatid, 115; comparison with 

 polar bodies, 116, 147, 148; com- 

 parison with spermatozoon, 128; 

 structure, 125 



spermatocytes, 133, 135, ff.; pri- 

 mary and secondary, 114, 115 



spermatogenesis, 18, 113, jf., 122, ff.; 

 diagram, 115 



spermatogonia, 114, 133 



spermatophores, 105, 106 



spermatosphere, 125 



spermatozoon (or spermatozoa), 97, 



ff., 115; accessory, 171; agglutina- 

 tion of, 167; behavior upon enter- 

 ing ovum, 172, ff., 181; comparison 

 with ovum, 150, 151; direction of 

 swimming, 166; entrance into 

 ovum, 167, ff.; entrance path, 

 185, 186; exclusion of, by ova, 

 170; flagellate, structure, 97, 98; 

 forms, 97, ff. 99; "giant," 101; 

 head of, transformed into pronu- 

 cleus, 181; human, size of, 100; lon- 

 gevity, 166; number, 100, 107-108; 

 penetration into ovum, 167; rate 

 of swimming, 166; size, 100; spiral 

 path, in swimming, 166; volume, 

 101 



Sphcer echinus, development in chem- 

 ically altered media, 320 ; of 



fused blastulae, 286 ; iso- 

 lated blastomeres, 281 ; 



parts of gastrulae, 283 ; larva from 

 dispermic ovum, 300; pseudo- 

 hybrids, history of chrpmatin, 302 



spindle, 51; chromatic, in Opalina, 

 62; intranuclear, 67; multipolar, 

 67 ; origin of , in Protozoa, 62; posi- 

 tion of, in cell, 230 



spinning activity, 149 



spireme, 45 



spongioplasm, 34; arrangement dur- 

 ing mitosis, 79 



spontaneous generation, 1 



spores, development from, 203; for- 

 mation, 4 



sporophyte, chromosomes, 161162 



squash-bug, see Anasa. 



star-fish, see Asterias, Astropecten. 



statoblasts, 7 



Steinbruck, 305 



Stephanosph&ra, conjugation, 193; 

 reproduction, 199 



Stevens, 311 



Stockard, 318 



Strasburger, 80, 136, 162 



stroma, of ovary, 111 



Strongylocentrotus, chromosomal va- 

 riation, 67; cleavage, 233; de- 

 velopment of isolated blastomeres, 

 282; history of chromatin in 

 pseudohybrids, 304 ; modified 

 chromosomes in ova, 314 



structure of protoplasm, 3436 



Styela, see Cynthia. 



sub-germinal cavity, 332 



Sumner, 354 



Surface, 248, 249, 252 



symmetry, of ovum and adult, 

 relation to first cleavage, 246; of 

 ovum, changes during fertiliza- 

 tion, 179 



