INDEX 
3 
References 
Arteries — continued 
of fishes. 75 
of man.452 
Arthropods, classified .... 9 
example of. 9 
number of. 9 
word explained.60 
Arthropods, summary of . . . 67 
Articulation of bones .... 434 
Artificial respiration .... 448 
Asepalous flowers. 202 
Aseptic, defined. 313 
Asexual reproduction, of ccelen- 
terates.163 
Ash, result of chemical change . 10 
Ash tree.364 
Ash wood.352 
Asparagus, a leafless plant . . 290 
beetles. 34 
fern, specialized stem of . . 263 
Assimilation, defined .... 5 
in plants.282 
Aster, a common weed . . . 301 
Atmosphere, composition of 11 , 12 
Attitude of early settlers 
towards forests .... 348 
Auditory organ of grasshopper . 24 
Auricles of heart.452 
Aves, class of vertebrates . . 9 
B 
Bacilli coli, tests for . . . . 518 
Bacillus, a form of bacteria . . 309 
Bacillus tuberculosis, cause of 
consumption.489 
Bacteria, action on lava . . . 375 
carried by insects .... 29 
cause of sour bread .... 427 
cause of sour milk . . . . 314 
classified. 9 
conditions necessary for 
growth.310 
control of.313 
decomposition of materials 
by.310 
discussed.309 
distributed by flies .... 29 
effect of enzymes and . . . 311 
forms of.309 
harm to teeth from .... 407 
are to pages 
Bacteria — continued 
harmful. 314 
helpful. 309, 311 
important plants .... 309 
in formation of soil .... 375 
injury caused to plant by . 315 
inoculation of soil with . . 259 
in relation to milk . . . . 313 
in roots of leguminous plants 
256, 311 
in warm milk.316 
laboratory study of. . . . 312 
life processes of.310 
multiplication of .... 311 
presence, in polluted water . 462 
prevention of growth of . . 497 
proper conditions for growth 
of.310 
shape and size . . . 309, 310 
source of disease .... 489 
summary of.317 
unfavorable conditions with¬ 
stood by.311 
where found.309 
Bacterial poison, toxin . . . 311 
Bailer in gill chambers of cray¬ 
fish .63 
Balanced diet.418 
Balancing, use of fins for . . 73 
Balancing organ, ear a . . . 475 
Ball and socket joint .... 435 
Balsam, adventitious roots on . 254 
Balsams, conifers.345 
Balsa wood.356 
Bananas, value of as food . . 245 
Barberry, host of black stem 
rust.388 
Bark of hemlock.346 
Barley, a cereal.244 
a monocotyledon .... 227 
member of the grass family . 295 
Barnacles, economic importance 
of.65 
Bass, a bony fish.71 
example of fish. 9 
Basswood, characteristics of . 352 
Bast fibers.262 
Bat, enemy of mosquito ... 56 
Beaks of birds, variations in . 109 
Bean, an irregular flower . . 204 
embryo, growth of ... . 220 
