428 



INDEX 



Maturation division, first in female, 212; 



first in male, 211; second in female, 



213; second in male, 212 

 Maturation spindle, 215 

 Mature egg, 211, 213 

 Mechanism, of development, 235-238; 



of heredity, 254; of mitosis, 79-80; 



of mutation, 347 

 Mecoptera, classified, 270 

 Medulla oblongata, 120; functions of, 



163 

 Medullary sheath, 160 

 Medusa, 97, 99, 186; of Bougainvillea 



ramosa, 96 

 Megapodes, disposition of eggs, 198, 199 

 Membranous labyrinths, 349 

 Memory, 162 

 Men, prehistoric, 337 

 Mendel, Gregor, 23, 251, 252 

 Mendelian heredity, 344 

 Mendel's law, 251, 252, 346 

 Meridional cleavage, 217, 218 

 Merozoites, 172 

 Merychippus, 324, 325,326,327; skull of, 



327; tooth of, 326 

 Mesentery, 115, 116, 210 

 Mesoderm, 115, 221, 222, 223, 224, 225, 



228, 229; formed by delamination, 



223 

 Mesodermal pouch, 222 

 Mesoderm formation, 221-223; in Am- 



phioxus, 222 

 Mesogloea, 65, 170 

 Mesohippus, 324, 325,327; skull of , 326; 



tooth of, 326 

 Mesozoa, classified, 270, 274 

 Mesozoic, 332, 352, 353; in time scale, 



315 

 Metabolic activities, 66; influenced by 



secretions, 154 

 Metabolism, 47, 48 

 Metacarpals, 138, 139 

 Metagenesis, 186 

 Metameres, 108 

 Metameric animals, 108 

 Metameric arrangement, modifications 



of, 108 

 Metamerism, 108; interpreted, 108 

 Metamorphosis, 206,231-233; in inverte- 

 brates, 231; in vertebrates, 232. 



(See also Larva.) 

 Metaphase, 71, 74, 77 

 Metatarsals, 138, 139 



Metazoa, 172, 175; colony formation in, 

 96, 100; fertihzation in, 180; organi- 

 zation in, 94 ; sexual reproduction in, 

 174 



Miastor, 181, 182, 209 



Miastor americana, 182 



Mice, birth stages in, 201; mutations in, 

 347 



Michigan rainfall, 294 



Microdrili, classified, 269 



Microgamete, 174, 176 



Micromeres, 218, 219 



Micronucleus, 81, 177, 178, 179, 180 



Microorganisms, 166 



Micropyle, in egg of Musca, 215 



Microscope, 7, 13, 15, 16, 165 



Microtus montanus, migration of, 301 



Middle ear, 226, 230 



Mid-piece of sperm, 216 



Migration, barriers to, 305; of birds, 300; 

 of clams, 303; of environment, 317; 

 of extinct animals, 316, 317; a factor 

 in distribution, 300; of fox sqiurrel, 

 306; of freshwater eels, 300; of 

 lemming, 300; oi Leptinotarsa decem- 

 lineata, 303, 306; of Microtus mon- 

 tanus, 301; normal, 301; periodic, 

 300; of protoplasmic substances, 80; 

 of sand grouse, 300; sporadic, 300 



Milk, a glandular secretion, 154 



Milk teeth, 323 



Mimic (see Mimicry) 



Mimicry, butterflies, 280; Cemophora 

 coccinea, 280; coral snake, 280; 

 syrphid flies, 280; wasps, 280 



Miniature wing in Drosophila, 345 



Miocene, 319, 321, 324, 325; in time scale, 

 315 



Miracidium, 182, 183 



Mites, parasitic, 279 



Mitosis, 70, 175; electromagnetic ex- 

 planation of, 79; generaJized account 

 of, 71-80; intranuclear, 78; mechan- 

 ism of, 79-80; in Protozoa, 81; 

 significance of, 78; variations in, 

 76-78 



Mitotic spindle, origin of, 76 



Mitrocoma cirrata, 106 



Model (see Mimicry) %* 



Moeritherium, 319, 320, 321 |' 



von Mohl, Hugo, 26 *-^ 



Moisture, an environmental factor, 283 



Molar teeth, in Palaeomastodon, 320  



