Index - 719 



Ribonudease, 135 



Ribonucleic acid (RNA), 136, 525; deoxyribonu- 

 cleic acid (DNA)-protein relationships, 525-26; 

 kinds of. 525-26; proteins, 22, 23, 25, 35, 83, 

 88, 110, 134-35 



Ribose. 80 



Ribosomal RNA, 525 



Ribosomes, 7, 25. 135 



Ribulose diphosphate, 165, 166 



Richards, A. N., 374 



Rickets, 353 



Ricketts, H., 602 



Rickettsia, 7. 602 



"Ringer's solution," 118 



Ringworm, 607 



Ris, H., 520 



RNA (see Ribonucleic acid) 



Rodentia, 675 



Root hair cells, 19, 22 



Root hairs. 245, 246, 247 



Root pressure, 252-53 



Rootlets, 245 



Roots, 238; economic importance of, 257; func- 

 tions of, 244-46; seed plants. 232-34 



Rotifer a, 641-42, 643 



Roundworms, 646 



Rous sarcoma, 48 



Rubin, S., 161, 162, 164 



Rusts, 173, 606, 607, 609 



Sacculina, 511 



Saliva, 298, 300; composition and functions of, 



301 

 Salivary amylases, 103 

 Salivary glands, 298, 300-03 

 Salivation reflex, 301-03 

 Salts, 71, 74-75; food substance, 127 

 Sand dollars, 663 

 Sandworms, 647, 648, 649 

 Sap, elevation of, 252-53; flow of, transpiration 



and, 251-52 

 Saprophytes, 174 

 Sarcodina, 625-26 

 Sarcolemma, 286 

 Sarcoplasm, 286 

 Scallops, 649, 652, 653 

 Sacaphopoda, 653 

 Schistosoma, 638-39 

 Schizomycophytes (see Bacteria) 

 Schleiden, M., 38 

 Schoenheimer, R., 133 

 Schultze, M., 38 

 Schwann, T., 38 

 Sclrweet, R.. 135 

 Science, method of, 12-14; progress of, 11-15 



Sclerenchyma, 243, 247 



Scorpions, 655 



Scrotum, 383, 384 



Scurvy, 347, 349 



Scyphozoa, 633 



Sea anemone, 631, 633-34 



Sea cucumbers, 660, 661, 663-64 



Sea lilies, 660, 661, 664 



Sea urchins, 660, 661, 663 



Secondary sexual characteristics, female, 388; 

 male, 384, 399 



Secondary spermatocytes, 54 



Secretin, 314 



Secretion, 199-200; effectors of, 440-41; of the 

 kidney, 376 



Secretory granules, 30 



Sedimentary rocks, 561 



Seed, 222; germination of, 222, 224, 225 



Seed plants, 615-21; bud development, 232; 

 cotyledons, 222-24; dicotyledonous, embryonic 

 development in, 230, 231; embryo sporophyte, 

 221-22; embryo structure, 222-24; floral parts, 

 nature of, 219; floral structure, variations of, 

 224—25; flower of, 216-19; fruit structure, vari- 

 ations of. 225-28; gametophytes, significance of, 

 221; gametophytes of the angiosperm, 219-21; 

 germination, 231-32; growth and development 

 of, 228-34; gymnosperms vs. angiosperms, 216; 

 leaf development, 232; life cycle of, 209, 216- 

 28; root development, 232-34; seed of, 222; 

 sporophyte generation, 216; vegetative methods 

 of reproduction, 234 



Segmentation, 647 



Segmented worms, 647-49 



Segregation. 481-84; Mendel's law of, 490 



Selaginella, 219; life cycle of, 214-16 



Selection (see Artificial selection; Natural selec- 

 tion) 



Selective breeding, 510, 516-17 



Self-pollination, 221 



Self-replication, 5 



Semen, 381, 385 



Seminal receptacles, 382 



Seminal vesicle, 383, 384, 385 



Semipermeable membrane, 113 



Sensations, perception of, 426-27 



Sense organs, 419-26 



Sensory tracts, 463-64 



Serai stages, 589 



Sere, 589, 590 



Serosa, 298 



Serotonin, 455 



Sex, inheritance of. 495-99; secondary character- 

 istics (see Secondary sexual characteristics) 



Sex chromosomes, 497-98, 507 



Sex-linked genes, 498-99 



Sexual differentiation, nongenetic, 499 



