INDEX 
11 
References 
Diphtheria (germ disease) . 448, 489 
antitoxin. 449 
carriers.500 
ten years of in France . . . 511 
treatment of .... . 507, 511 
Diptera (order of insects) . . 29 
described.29,54 
Dirty milk, bacteria in ... 313 
Disk flowers.206 
Disease, cause of.487 
of plants, necessity for 
knowing . . . . . . 380 
of respiratory tract .... 448 
results of. 514 
student report on ... . 487 
summary of. 495 
Diseases, cause'd by abnormal 
growth of tissues .... 487 
caused by bacteria .... 488 
caused by plants or animals . 488 
caused by poisons, list of . . 487 
of respiratory tract .... 448 
Disinfectants. 507, 512 
Disinfection.512 
Disk, central, of starfish . . . 169 
adhesive, of starfish . . . 171 
Disk-flowers of composites . . 206 
Dispersal of seeds, agencies for 240 
by animals.241 
by pappus and hooks . . . 241 
by water.241 
by wind.241 
necessity for.240 
Disposal of sewage .... 461 
Dissected leaves of crowfoot 
family.297 
Dividing cells of pleurococcus . 305 
Dividing egg, becoming tadpole 91 
of frog.91 
Division of Drugs.505 
Division of labor .... 153, 154 
in sponge.155 
in volvox.153 
Division of Publications, 
W ashington . 526 
Dodder.290 
Dog.: . . 134 
Domestic fowl, wings of . . . 108 
Dormancy in seeds .... 223 
Dorsal blood vessel of earth¬ 
worm .182 
to pages 
Dorsal surface of earthworm 179 
Double flowers defined . 204 
Dough in bread making . . . 427 
Down on wind-distributed 
seeds.241 
Downy mildew. 531 
Downy woodpecker, a per¬ 
manent resident . . . Ill 
food of. 114 
Dragon flies, enemies of mos¬ 
quito . 56 
member of Odonata ... 29 
Dressed lumber, defined. . . 363 
Drills, a method of planting 376 
Drones (bees) ..46 
Drowning, a form of suffoca¬ 
tion . 447 
Drupe, defined.237 
Dry farming. 391 
Dry fruits, bean an example of 237 
Drying, protection of bacteria 
from.. 311 
Drying fruit, purpose of . . . 313 
Dry season, effect of, on annual 
ring.266 
Dry seasons, effect of, on size 
of cells.266 
Ducks, feet of.108 
Duration of roots.252 
of stems.261 
E 
Eagle, a scavenger.116 
claws of.108 
wings of.107 
Ear, organ of sound .... 476 
balancing organ. 475 
membrane of frog .... 83 
of grasshopper.24 
pistillate flower of corn . . 204 
sense organ. 475 
wax in.476 
Earliest homes of man . 400 
Earthworm, discussed .... 178 
economic importance of . . 183 
example of worms .... 9 
excretions of.180 
illustration of true worms . 178 
laboratory study of . . . 180, 182 
life history of.182 
