28 
INDEX 
References are to pages 
produced by stamens . . . 
202 
Preparation of foods, discussed 
426 
sacs of pine. 
343 
of soil. 
231 
tube, formation of ... . 
201 
Preservation of wood . 
353 
of pine. 
210 
Preservatives, list of . 
314 
Pollen grains, growth through 
use of, in milk . . 
314 
pistil ........ 
2 ; 12 
Preventable diseases . 
497 
Pollination, by wind .... 
210 
Prevention of communicable 
definition of. 
208 
diseases . . . 
497 
step in production of fruit . 
209 
of epidemics . 
515 
Pollution of water . . . 462, 508 
Preventive measures against 
Polytricum, laboratory study of 
330 
sickness. 
517 
Pome, a fleshy fruit .... 
237 
Primary root. 
250 
Pond scum, habitat of 
305 
Problem of sewage disposal 
443 
Pond snail, discussed .... 
190 
Proboscis of butterfly . . 
39 
Poplars, as shade trees . 
364 
Products of cotton seeds 
222 
rapid growth of. 
352 
of photosynthesis 
• • 
279 
Poppy, capsule of . . . 238, 241 
Propolis, use of, by bees . 
, . 
49 
Pores of sponge. 
156 
Properties of wood 
354 
Porifera, classified. 
8 
Prop roots of corn . 
253 
Pork, inspection of . . 177, 500 
Protection of forests . 
357 
trichinella in. 
176 
Protective coloration, of birds . 
110 
Portal vein. 
414 
of grasshoppers . . . 
21 
Position of stems. 
260 
Proteid substances in 
flour 
Potassium, a chemical element 
source of food for 
yeast 
found in all living things 
13 
plant. 
427 
contained in food .... 
413 
Protein, a class of foods 
13, 415, 416 
Potassium permanganate, a dis¬ 
in bean . 
228 
infectant . 
512 
product of photosynthesis 
279 
Potassium phosphate in Pas¬ 
stored by bean . 
222 
teur solution. 
322 
Proteins of serum . 
428 
Potato, a food plant of the 
Prothallium of fern 
336 
nightshade family . . . 
301 
Prothorax of grasshopper 
23 
beetle, injurious insect . 34, 35 
Protonema, of fern 
336 
wart, a disease. 
380 
of moss. 
329 
discussed. 
382 
Protoplasm, of cell . . . 
7 
Poultry destroyed by certain 
of pollen grain 
209 
hawks. 
115 
Protozoa, cause of disease 
489 
Powdery mildew. 
531 
classified . ... 
8 
Power of health officials . . . 
519 
flagellate. 
149 
Practical problems connected 
number of kinds of . . 
8 
with respiration and ex¬ 
resemblance to bacteria 
309 
cretion . 
443 
simplest animals . . . 
141 
Praecocial birds, defined . 
113 
Protozoa and alcohol . . 
150 
Prairie dogs, harmful mammals 
134 
Protozoan cell, described 
141 
Prairie horned larks at seed 
Protozoan diseases . . 
494 
station. 
118 
Pseudopodium of amoeba 
143 
Prairies suited to raising of corn 
296 
Ptarmigan, protectively colored 
121 
Praying mantids, a family of 
Pteridophytes, classified . 
9 
Orthoptera. 
29 
Pteris, described 
261, 
333 
Predigested foods, use of . . 
430 
Ptyalin, an enzyme 
411 
