INDEX 
637 
Segregation, law of, 555 
Mendelian, 554, 556 
Selaginella, 382, 384, 431 
amoena, 383 
Kraussiana, 387 
life-cycle of, 388 
Martensii, 385 
Watsoniana, 384 
Wildenovii, 383 
Selaginellales, 382. 388 
Selection, natural, 191 
Selfing, 560 
Self-pruning, 180 
Semi-parasitism, 341 
Sempervivum tabulaeforme, 41 
tectorum, 350 
Senebier, Jean, 74 
Senna, wild, 467 
Sensitive plant, 122 
Sepals, 435 
Serum-therapy, 314 
Seta, 204 
Sex, determination of, 358 
meaning of, 360 
problem of, in plants, 344 
Sex-organs, differentiation of, 356 
Sexual characters, secondary, 358 
Sexuality in molds, 353 
in Spirogyra, 355 
Shaggy-mane mushroom, 289 
Shelf-fungus, 303 
Shoot, 9 
Sigillarias, 612, 613 
Silique, 463 
Siphonogamy, 406 
Skein, nuclear, 186 
Skunk cabbage, 499, 500 
Solanaceae, 480 
Solanum 335 
Dulcamara, 481 
integrifolium, 545 
nigrum. 545 
Solanum tuberosum, 347, 480 
Solidago ulmifolia, 340 
Soredia, 330 
Sorghum halpense, 496 
Sorus, 154 
Soy bean, 317 
Spartina, 293 
Spathyema fcetida, 496 
Species, elementary, 530 
origin of, 510, 587 
Spermatophytes, 408 
Sphaerothica phytoptophyla, 292 
Sphagnum, 193, 194, 200, 202, 204, 
348 
acutifolium, 198 
cuspidatum, 199 
cymbifoliunx 195 
life-history of, 203 
squarrosum, 198 
Sphagnales, 193 
Sphenophyllum cuneifolium, 372 
Sphenophyllales, 618 
Sphenopsida, 618 
Sphenopteris Hceninghausi, 592 
Spike, 459, 493 
Spikelets, 495 
Spirogyra, 344, 345, 353, 355, 364 
Sporangiophores, 371 
Sporangium, 155, 156, 157 
Spore-mother-cells, 158 
Spores, 155 
dispersal of, 164 
germination of, 165 
swarm-, 251 
Sporogonium, 201 
Sporophylls, 156, 159 
Sporophyte, 181, 201 
development of, 364 
evolution of, 574 
Spruce, 140 
Staff-tree, 481 
S'-'k-cell, 428 
