INDEX 



Boldface numbers refer to pages bearing illustrations of items indexed. 



Abiogenesis, 159 

 Absorption, 106 



of food, 104 

 Acanthocephala, 275 

 Accidental dispersal, 320 

 AcetabuliuTi, 92, 93 

 Acetylcholine, 148 

 Acids, 35, 36 

 Actinomorphes, 246 



Adaptation, as quality of whole organism, 

 364 



resulting from natural selection, 363- 

 365 



taxonomic ranks showing, 363, 364 

 Adipose tissue, 82 

 Adrenal glands, 153, 154, 155 

 Adrenalin, 155 

 Adsorption, 45 

 Afferent neuron, 144, 145 

 "Age and Area" hypothesis, 310 

 Age of earth, 331 



in geological periods, 331 

 Alecithal egg, 199 



cleavage of, 201 

 AU-or-none rule, 53 

 Altricial birds, 190 

 Alveolar gland, 84, 85 

 Alveoli, 114, 115 

 Amino acids, 41 

 Amitosis, 62 

 Ammonite, 332 



sutures of, 343 

 Amoeba, 24, 51, 260 



food vacuole of, 101 

 Amphibia, 277, 279 



evolution of, 335 

 Amphicoelous vertebrae, 92 

 Amphineura, 271, 272 

 Amphioxus, 276 

 Amylopsin, 105 

 Anabolism, 46 



Analogy, 251, 252 



Anaphase, 56, 58 



Anatomy, comparative, 13-14 



Anaximander, 2 



Animal communities, 290-291 



relation of, to vegetation, 305, 306 

 Animal pole, 199 

 Anisogamete, 161 

 Annehda, 269-270 

 Anthophysa, spheroid and dendritic 



colony of, 68 

 Anthozoa, 263, 264 

 Anus, of earthworm, 101, 102 



in embryo, 208, 210, 212 



in vertebrate, 103 

 Apathetic animals (Lamarck), 246 

 Appendicular skeleton, 90, 92, 93 

 Arachnida, 273, 274, 275 

 Archenteron, 73, 204, 206 

 Archeozoic, 330 

 Archiannelida, 270 

 Aristotle, 3, 4, 5, 6 

 Arms, homology of, 253 

 Arteries, 122, 123, 129 

 Arterioles, 129 

 Arthropoda, 272-275 

 Artiomorphes, 246 

 Ascaris, chromosomes in, 59 



cleavage of, 203 

 Ascorbic acid, 110 

 Asexual reproduction, 159, 169-174, 176 



of Paramecium, 169 

 Assimilation, 46. 49 

 Association neuron, 145, 146 

 Associations, 290-291 



in vegetated areas, 305, 306 

 Asteroidea, 268 

 Asymmetry, 78, 79 

 Atolls, 303 

 Atom, 31-33 



"Atomic" theory of the universe, 3 

 Auricle, 123, 124 

 Auriculoventricular bundles, 128 



411 



