VI 



BIOLOGY AND HUMAN LIFE 



Insecta (in sek'td), 82 ; economic 

 value of, 451 f. 



Insects, structure of, I5f. ; relation 

 to flowers, 34, 47, 49 f.; injurious, 

 317 f., 557, 561 ff.; useful, 426; re- 

 production of, 487 ; and useful 

 plants, 563 ff. ; and useful animals, 

 566 f. ; methods of fighting, 567 ff. 



Inspiration (breathing), 162 



Instincts, 241 f.; modification of, 242 f. 



In'su lin, 177 



Intelligence, 538 ; applied to human 

 affairs, 589 



Interdependence, between organisms, 

 33 f., 50, 532 f.; of flowers and in- 

 sects, 49, 571 ; of people, 407, 544 



Internal secretions, 178, 212 



Intestines, 132, 133 f., 136 f., 184; 

 length of, 133; lining of, 135; 

 evacuation of, 137 



Irritability, 20, 22,37,216; specializa- 

 tion of, 216 ff. 



Jack-in-the-pulpit, 53 

 Jellyfish, 80 



Kidneys, 184, 194; hygiene of, 194 ff. 



Labor, division of, 31 ff., 113, 208 ff., 

 393, 407, 416, 472, 539 f. See also 

 Work 



Ladybug, 452, 567 f. 



Lar'vfl, 28 



Layering, 117 



Lazear, Dr. Jesse W., 324, 325 



Leaf, 13 f., no, in; structure of, 

 108; and light, 112; uses of, ii2f. 



Legs of insect, 15 



Le gu'min, 102 



Lenticels (len'ti selz), 112 



Lep i dop'ter a, 30, 84 



Lice, 328 



Lichens (irkenz), 79, 433 



Life, what it is, 3 f ., 208 ; origin of, 

 23; and air, i6of. ; unity of, 208 ff. ; 

 changing conditions of, 379 f . ; strug- 

 gle for, 533 ff. 



Light, in food-making, 108 ; influence 

 on growth of plant, 112 



Lily, economic value of, 436 



Liver, 132, 134, 135, 177 



Liverworts, 79 



Living bodies, characteristics of, 17 ; 

 osmosis in, 127 



Lobster, appendages of, 35 ; breath 



ing in, 451 ; regeneration in, 482 

 Locusts, 27, 563 f. 

 Lungs, 161, 162, 183 

 Lymph (liuif), 181 



Madder, economic value of, 443 

 Malaria, 303, 309, 322 f.; cause of, 



449 

 Male and female, 472 f. 



Mallow, economic value of, 441 



Malnutrition, 148, 288, 368 



Mam ma'li a, 89 



Mam'mals, structure of, 16, 275, 282; 

 economic value of, 460 ff . ; repro- 

 duction in, 488 



Man, body cavity of, 274 ; viscera of, 

 276; skeleton of, 278, 282 ; depend- 

 ence of, 298, 549 ff. ; and the mos- 

 quito, 323 ; struggle of, 537 ff. ; 

 relics of, 541 ; birds in relation to, 

 574 ff. ; mastery of environment by, 

 580 ff. ; and eugenics, 583 f., 589 ; 

 heredity in, 584 ff . • 



Maple, economic value of, 441 



Marsupials (inarsu'pi dlz), 89, 488 



Meals, number and frequency, 152, 



154 

 Meal-worm, 564 



Meat in diet, 147 



Medicine. See Drugs 



Men'del, Gregor, experiments of, 

 507 f. ; laws of, 508 ff., 522 ff., 584 



Meningitis, 304 



Me tab'6 ITsm, 140 



Met a mor'pho sis, 29 ; in animals, 

 285, 456, 457 ; in man, 286 



Metchnikoff, fihe, 178 



Microbes. See Bacteria 



Mi'cro pyle, 44, 67 



Milk, standards for, 355; pasteuriza- 

 tion of, 356 f. 



Milt, 484 



Mind, influence of, on health, 263 f. ; 

 unifies the organism, 268 f. 



Minerals, in soil, 92 ; in plants, 92 f. ; 

 in food, 101, 141, 146, 147 ; in 

 manufacture of proteins, 109 



Mint, economic value of, 443 



Mite, 335 



Moisture and ventilation, 169 f. 



Mold, reproduction in, 76 



M61 liis'c^, 84 



M6riiisks, economic value of, 452 f. 



