36 



INDEX 



References are to pages 



Slug- (garden) 



Slugs, examples of mollusks 

 Small cells, position of in annual 



99 

 94 



290 

 116 

 168 

 251 

 250 

 234 

 14 



Small intestine, of frog . . . 



of man 



Smallpox, Jenner and .... 

 lessened by vaccination . . . 



probable cause of 



Smell, organ of, in grasshopper 

 Smoke, result of chemical 



change 9 



of puffball 364 



Smoker's heart, how affected . 227 

 Smoking, charts showing effect 



of 228, 229 



Smoking and scholarship . . 229 



Smoking of meat, purpose of . 347 



Snails, discussed 98 



example of Gastropoda (fig.) 6, 98 

 examples of mollusks . . . . 6, 94 



respiration in 99 



shells (fig.) 99 



tongue of (fig.) 98 



Snakes, (black,) harmful . . . 132 



discussed 131 



examples of Reptilia ... 7, 129 



food of 132 



Sneezing, distribution of germs 



by 197 



Snowy owl a winter visi- 

 tant 141 



Soda, a nutrient 176 



preservative 348 



Sodium carbonate in artifi- 

 cial pancreatic juice . . 173 

 Sodium chloride, scientific 



name for common salt . . . 173 



Soft palate of man .... 166 

 Soft-shelled clam, an edible 



mollusk (fig.) 100 



discussed 100 



Soft-shelled crab (fig.) ... 91 

 Soil, an element of success in 



agriculture 320 



upper layers, habitat of bacteria 344 



Soil bacteria (fig.) ...... 344 



Soldiers, a class of ants ... 41 

 Soles of feet, animals that walk 



on 152 



Solomon's seal, stems of . . 285 

 Song sparrow, at hemp and 



millet station 148 



killed by hawks 145 



useful bird 144 



Sori, of ferns (figs.) . . . .370,371 



Sorus, position of (fig.) . . . 372 



section of (fig.) 372 



Sounds from sound waves . 218 

 Sour, a fundamental taste . . 165 

 Source of man's food sup- 

 ply 320 



Sources of danger in milk . 349 

 Souring of milk, cause of . 348, 350 



Sparrow, chipping, useful bird 144 

 English, chatter attracts other 



birds 148 



example of bird 7 



fox, example of transient bird 141 

 hawk, destroyer of grass- 

 hoppers 22 



destroyer of cicadas ... 26 



Sparrows, seed-eaters .... 148 



Spawn, migrations of fishes to 109 

 Spearmint, member of mint 



family 331 



Special modifications of 



plants 389 



Special senses, organs of . . 215 

 Species defined by Linnaeus 303 

 Specific names used by Lin- 

 naeus 303 



Sperm, a sexual cell 4 



cells of fern 371 



of moss plant 365 



volvox 56 



nucleus of pollen grains . . . 299 



Spermaries of hydroids . . 68 

 Sphinx moth from tomato 



worm ........ 34 



Spicules, described (fig.) ... 59 

 Spider, member of Arachnida 



(fig.) 91,92 



Spinal column of man, curves 



of 187 



Spinal cord, part of nervous 



system 119 



Spines of echinoderms ... 71 



Spiracles, location of ... . 16 



of grasshopper ...... 15 



