INDEX 
33 
References are to pages 
Silica in corn stem.268 
in skeleton of sponge . . . 158 
Silique of mustard family (fruit) 298 
Silk of corn, attachment of 204, 225 
the style.198 
Silver maple, poor shade tree . 364 
Simple leaf, of beech family . 297 
defined.277 
Simplest green plants .... 304 
Sinus, defined.64 
Siphonaptera, an order of in¬ 
sects .29 
Siphons of clams.185 
Siphons of soft-shelled clam 191 
Sirup, maple .351 
Skate, edible fish.79 
Skeletal structures, student re¬ 
port on.436 
Skeleton, external, of corals 167 
of crayfish.60, 61 
of man.433 
characteristics of . . . . 434 
summary of.441 
of protozoa.149 
Skin, as sense organ .... 458 
described.458 
example of organ .... 7 
of fruit.243 
Skunk, example of harmful 
mammal.137 
Sleep, amount needed . . . 476 
Sleep movements of plants 291 
Sleeping sickness, how spread . 494 
probable cause of ... 489 
Slimy feeling of spirogyra . 307 
Slimy substances of sponge re¬ 
moved by bacteria . . 311 
Slips producing adventitious 
roots.254 
Slug (garden).190 
Slugs, examples of mollusks 185 
Small cells, position of, in an¬ 
nual ring.266 
Smallest plants.309 
Small intestine, of frog ... 86 
of man.408 
Smallpox, Jenner and .... 510 
lessened by vaccination . • 510 
probable cause of . • • 489 
Smell, organ of, in grasshopper 21 
sense of.472 
Smilax. 263, 290 
Smoke, result of chemical 
change.10 
of puffball.328 
Smoker’s heart; effect of to¬ 
bacco illustrated .... 482 
Smoking and scholarship . . 485 
Smoking of meat, purpose of 313 
Snails, discussed.189 
examples of mollusks . 9, 185 
respiration in.190 
tongue of.190 
Snakes (black), harmful . . . 102 
discussed.101 
examples of Reptilia . . 9, 99 
fear of.102 
food of.101 
Snowy owl, a winter visitant . 112 
Soap in cosmetics.504 
Soda, a nutrient, use of . . . 416 
preservative.314 
Sodium carbonate in artificial 
pancreatic juice .... 413 
Sodium chloride, scientific name 
for common salt .... 412 
Soft palate of man.406 
Soft-shelled clam, an edible 
mollusk.193 
discussed.193 
Soil, an element of success in 
agriculture.376 
upper layers, habitat of bac¬ 
teria .310 
Soil bacteria.256 
Soldiers, a class of ants ... 52 
Soles of feet, animals that walk 
on. 126 
Solitary flower.213 
Some general plant problems . 380 
Song sparrow, at hemp and 
millet station.118 
killed by hawks.115 
useful bird.H4 
Sorghum.421 
Sori, of ferns.334 
Sounds from sound waves . 475 
Sour, a fundamental taste . . 405 
Sour bread, cause of ... . 427 
Source of malarial parasite . 493 
Source of man’s food supply . 419 
Sources of danger in milk • 315 
