24 
INDEX 
References 
Movements, of leaves . . . 290 
of plants.369 
Mucous glands of fish ... 72 
Mucus, use of, by clam . . . 188 
Mule.129 
Mullein, flowers of.217 
Multiple fruits.240 
Muscle, bundle.437 
Muscle cells, heart .... 437 
fibers.437 
involuntary.437 
voluntary.437 
Muscles, color of.436 
involuntary.437 
of man, discussed . . 432, 436 
scars of clam.186 
voluntary.437 
Mushrooms, edible fungi 324 
poisonous.324 
Mustard, a common plant fam¬ 
ily . 222, 298 
Muzzling of dogs.509 
My a arenaria, edible clam . . 193 
Myosin.14 
Myriapods, discussed .... 66 
N 
Nails, origin of.459 
Narcotic, defined.479 
Narcotics, use of.506 
Nasal cavity of fish .... 75 
Nasturtium flower, example of 
adaptations.196 
National forest preserves . 361 
Natural enemies of potato 
beetle.36 
Natural gas, formation of . . 340 
Natural immunity.510 
Natural rate of breathing . . 446 
Nectar, relation to pollination 
by butterfly . . . . 39, 40 
sought by insects . . 199, 208 
Needle-like leaves of pine . 343 
Need for a study of forestry 347 
Nephridia of earthworm . . . 180 
Nereis, an annelid worm 184 
Nerve cells.466 
of mollusks.188 
Nerve fibers, defined . . 466 
description of.466 
are to pages 
Nerve fibers — Continued 
gray substance of ... 468 
white substance of . . . . 468 
work of.470 
Nerve pathways in midbrain 89 
Nerve supply of muscles . . . 438 
Nerves, cranial, of frog ... 89 
location of.89 
of earthworm.181 
of frog.89 
of mollusks.188 
Nervous system, growth of . . 468 
in grasshopper.25 
of crayfish.64 
of earthworm.181 
of frog.88 
of man.466 
parts of.466 
summary of.485 
Nest-building of birds . 112 
Nesting boxes.119 
Net-veined leaf.276 
New discoveries, discussed . . 521 
New ideas, value of ... 526 
Nighthawks, destroyers of mos¬ 
quitoes .56 
food of.115 
Nightshade family, character¬ 
istics of.300 
Nissl bodies.481 
Nitric acid, test for protein . . 228 
Nitrogen, a chemical element . 13 
gathered by bacteria . 256, 311 
in lipoid.480 
proportion of, in living things 13 
Node of corn stem.268 
Non-motile cells (eggs) of moss 
plants.329 
Non-smokers, scholarship of . 485 
Normalbodytemperatureof man 459 
Norway maple.364 
Nose, sense organ.472 
Notochord, embryonic structure 
of fishes.68 
Nourishment, defined .... 415 
Nucellus.219 
Nuclei of pollen and egg . . . 212 
Nucleoli of cells. 7 
Nucleus, of cell. 7 
of nerve cell, action of alcohol 
upon.481 
