INDEX 



443 



Pea, reproduction, 226. 



Pear, 325. 



Pearl-button industry, 356, 357. 



Pearls, 356. 



Peas, value as food, 124. 



Pellicle, of Paramecium, 98. 



Pepsin, 153, 154. 



Peptones, 154, 157. 



Perfumes, animal, 355. 



Pericardium, 169. 



Peristaltic movements, 153. 



Perspiration, 189, 190. 



Petals, 31, 32. 



Petiole, defined, 76. 



Petri dishes, 254. 



Phagocytes, 164, 165. 



Pharynx, 147, 150. 



Phenolphthalein, 70. 



Phloem, 90. 



Photosynthesis, 83. 



Phototropism, 16, 79-80. 



Phylloxera, 363. 



Phylum, in classification, 235. 



Physicist's view of the environment, 8. 



Physiological division of labor, 108- 



109. 

 Physiology, 1. 

 Pigeon, experiment with Vitamin B, 



123. 

 Pimples, 113. 

 Pinworms, 288. 

 Pisces, 243. 

 Pistil, 32. 

 Pitcher plant, 92. 

 Pith, 87, 88, 89. 

 Pith rays, 88, 89. 

 Pituitary gland, 167. 

 Placenta, 232. 



Plague, 266, 271, 276. 285, 286, 287. 

 Plankton, 348, 370. 

 Plant breeding, 384-391. 

 Plant cell, typical, 46, 49. 

 Plants, 49, 51-106; 



classification, 234-237 ; 



diversity of form, 43 ; 



drug-producing, 331, 332; 



effect of light, 79-80; 



exert energy, 84; 



fibers, 329-331 ; 



give off oxygen in sunhght, 82, 85 ; 



Plants, harmful, 331-333; 



in relation to animals, 4, 30-31, 35, 

 40, 102-106; 



influence of environment, 14-21 ; 



need mineral matter, 65, 66 ; 



oil from, 331; 



primary needs of, 107; 



reproduction, 219-226; 



respiration, 86; 



responses in, 192-196 ; 



seed dispersal, 39-41 ; 



simplest, 95; 



special digestive organs, 92 ; 



summary of the functions, 92-94; 



uses to man, 2-3, 5, 85, 323-333 ; 



without chlorophyll, 334-343 ; 



see also Bacteria and Fungi. 

 Plasma, 162, 164, 165, 168. 

 Plasmodium, 279. 

 Platyhelminthes, 240. 

 Pleura, 180. 



Pleurococcus, 96, 97, 219, 220. 

 Plumule, defined, 52. 

 Pneumonia, 264. 

 Pocket garden, 67. 

 Poison ivy, 331. 

 Poisons, 271, 272 ; 



alcohol, 140; 



plant, 331, 333. 

 Pollen, 32 ; 



grains, 224; 



growth, 224, 225, 226. 

 Pollination, 35, 36, 37, 38, 39; 



artificial, 386. 



cross and self, 35. 

 Pond scum, 223. 

 Pons, 200. 



Porifera, classified, 239. 

 Porkworm, 288. 

 Portal circulation, 172. 

 Posture, 114, 115. 

 Potato beetle, 361. 

 Potatoes, 324, 325; 



starch in, 129 ; 



value as food, 120, 123. 

 Precipitins, 165, 276. 

 Preservatives, of food, 344, 345. 

 Pressure, sense of, 202. 

 Pressure cooker, 344. 

 Primates, 249, 250. 



