578 



INDEX 



Microgromia, 196. 



Micronucleus, 155, 178. 



Microscope, 131. 



Microstoma, 256. 



Mid-brain, of frog, 416; see also 



Mesencephalon. 

 Millipede, see Myriopoda. 

 Missing links, 518. 

 Mitochondria, 135. 

 Mitosis, 137, 138; in Protozoa, 171, 



185; significance of, 140. 

 Mnemiopsis, 281. 

 Mceretheriian, 517, 518. 

 von Mohl, 132. 

 Mollusca, 246, 321; classification of, 



238, 240, 241. 

 MoUuscoida, 238, 240, 241. 

 Molting, of exoskeleton, 325, 345. 

 Monarch butterfly, 380. 

 Monocystis, 190, 191. 

 Mono-hybridization, in Drosophila, 



478; in fowls, 467; in mice, 466, 



475, 476, 477; in peas, 462, 463, 



465. 

 Monomorium minimum, 394. 

 Monosiga, 155, 175. 

 Morgan, 470, 471. 

 Morphology, 2, 3, 5, 6; of vertebrate 



body, 38. 

 Mosquito, 375, 385, 386; in relation 



to malaria, 207, 208. 

 Moths, 375, 381, 382. 

 Motorium, 182. 

 Mouth, of Amphioxus, 398; of ccelen- 



terates, 281; digestion in, 82; of 



earthworm, 283, 292; of fish, 45; 



of frog, 42; of Hydra, 249; of 



locust, 354; of Nereis, 312. 

 Mouth parts, of cockroach, 346; see 



also Oral appendages. 

 Mucous membrane, 150, 300, 417. 

 Mud-dauber, 389. 



Multicellular animals, see Metazoa. 

 Murgantia, 379. 

 Musca domestica, 384, 385. 

 Muscle, cardiac, 146; non-striated, 



146; segments of, 412, 414, 429; 



striated, 147. 



Muscles, 41, 42, 417; antagonistic, 

 68, 70; of earthworm, 300. 



Muscular system, 50, 68. 



Mutation, 486, 561. 



Mutation Theory, criticism of, 560; 

 history of, 557; and work of de 

 Vries, 558; in relation to Theory 

 of Natural Selection, 559. 



Myelencephalon, 116; see also Me- 

 dulla. 



Myriapoda, 241, 339, 340. 



Ncegleria gruberi, 163. 



Nasal cavity, 43, 44. 



Nasal pits, of frog, 414. 



Natural history, 9. 



Natural sciences, 1. 



Natural Selection, Theory of, 25, 496; 



criticism of, 555; history of, 544; 



origin of species by, 546. 

 Naturalistic theory, of origin of life, 



492. 

 Nauplius, 336. 

 N^auiilus, 513. 

 Neanderthal man, 534, 535. 

 Nemathehninthes, 237, 240, 241. 

 Nematocyst, 250, 252, 255. 

 Nematoda, 241. 

 Nephridiopore, 285, 290, 296. 

 Nephridium, 289, 294, 295, 300. 

 Nephrostome, 296. 

 Nereis, 311, 313. 

 Nerve cells, of Hydra, 252, 260, 266, 



267; see also Nervous tissue. 

 Nerve centers, 118. 

 Nerve cord, of earthworm, 279, 289, 



298, 300; of locust, 358. 

 Nerve fibers, 149. 

 Nerves, 149; autonomic, 67; cranial, 



66; of earthworm, 289, 297; 



spinal, 66, 108; sj-mpathetic, 67. 

 Nervous coordination, 106, 117, 128; 



by excitation, 127; by inhibition, 



127. 

 Nervous impulse, 108; adjustment of, 



116; transmission of, 115, 126. 

 Nervous sj^stem, central, 63, 115, 317; 



of earthworm, 289, 297; of frog, 



