INDEX 



445 



Root hairs, 68, 69, 70, 72. 



Root pressure, 91. 

 Roots, 66-73 ; 



downward growth of, 66-67; 



food for man, 325 ; 



give out acid, 70 ; 



growth toward water, 67 ; 



primary, secondary, and tertiary, 

 66; 



root hairs, 68, 69, 70, 72 ; 



structure of, 67, 68, 69. 

 Ross, Major, investigator, 411. 

 Rotation of crops, 341, 342. 

 Roughage, in foods, 124. 

 Roundworms, 240, 288, 289. 

 Roux, investigator, 409. 

 Russian thistle, 333. 

 Rusts, 337. 

 Rye, 328. 



SaHva, action of, 149. 

 Sahvary glands, 149. 

 Salmon, 352, 373, 374. 

 Salt, a food, 121 ; 



a food preservative, 344. 

 Sanitarium for tuberculosis, 309. 

 Sanitation, 22. 

 Saprophytes, 334. 

 Scallops, 349, 371. 

 Scarlet fever, 266, 268, 269; 



Dick test, 273. 

 Scavengers, 357, 360. 

 Schaefer method, of artificial respira- 

 tion, 182, 183. 

 Schick test, 273. 

 Schleiden, biologist, 405. 

 School, surroundings, 297. 

 School and infant hj^giene, work of 



health board, 310, 311. 

 Schwann, biologist, 406. 

 Scurvy, dexiciency disease, 123. 

 Sea anemone, 240 ; 



symbiosis, 105. 

 Sea cucumber, 241. 

 Sea lily, 241. 

 Sea Hon, 249. 

 Sea urchin, 241. 

 Seals 354. 



Secretin, normone. 155, 166. 

 Secretion, 148, 166. 



Seeds, development, 226, 361 ; 



dispersal, 39, 40, 41 ; 



food of man, 325-328. 

 Seeing, 205-206. 

 Segmented worms, 241. 

 Segments, of insect, 25. 

 Segregation, law of, 388. 

 Selection, natural and artificial, 383, 



384. 

 Selective planting, 385. 

 Self-pollination, 35, 36. 

 Semicircular canals, 204. 

 Semi-permeable membrane, 71, 72. 

 Sense organs, 196, 197, 202-206 ; 



health habits, 213 ; 



of frog, 110. 

 Sensory hair, 196, 197. 

 Sensory nerves, 198. 

 Sepal, 31, 32. 



Septic sore throat, 266, 269. 

 Septic tank, 297. 



Serum, antitoxin, 272, 273, 274, 276. 

 Sewage disposal, 304, 305, 306 ; 



pollution of water supply, 303-305. 

 Sexual reproduction, 222, 223 ; 



in animals, 227-232 ; 



in plants, 223-226. 

 Shad, 373. 

 Sheep, 353, 354; 



fiver fluke, 228. 

 Shelf fungus, 335. 

 SheUac, 357. 

 Shoulders, round, 114. 

 Shrimps, 350; 



ears, 197. 

 Sieve tubes, 87, 89, 90, 91. 

 Silk industry, 353, 354. 

 Silkworm, 27, 353, 354. 

 Simplest organisms, 95. 

 Siphonaptera, 242. 

 Sirenia, 249. 

 Skeleton of man, 114 ; 



of vertebrates (dog), 243. 

 Skin, 112, 113; 



as an organ of excretion, 189 ; 



frog's, 110; 



infections, 113; 



regulates body heat, 190. 

 Sleep, necessity of, 212. 

 Sleeping places, outdoor, 185. 



