GLOSSARY 



Abiogenesis: The discredited hypothesis that life may orig- 

 inate spontaneously in lifeless matter, i.e., apart from the 

 influence of living matter. 



Adaptation: (1) The reciprocal aptitude of organism and 

 environment for each other; (2) a structure, modification 

 of structure, or behavioristic response enabling the organ- 

 ism to solve a special problem imposed by the environ- 

 ment; (3) the process by which the organism's adjust- 

 ment to the environment is brought about. 



Allelomorphs: Genes located opposite each other on homolo- 

 gous chromosomes and representing contrasting characters'; 

 they are separated during meiosis according to the Men- 

 delian law of segregation, e.g. the genes for red and white 

 in Four o'clocks which when united give rise to pink, and 

 when segregated, to red and white flowers respectively, 

 are allelomorphs of each other. 



Alluvial: Pertaining to the Alluvium, which consists of 

 fresh-water deposits of the Pleistocene and Recent series, 

 to be distinguished from the Diluvium which consists of 

 older Pleistocene formations. 



Amino-acids: The chemical building-stones of the proteins 

 — organic acids containing one or more amino-groups 

 ( — NH,) in place of hydrogen, e.g., amino-acetic acid, 

 CH.-NH^-COGH. 



Amnion: A membranous bag which encloses the embyro in 

 higher vertebrates. The lower vertebrates, namely, fishes 

 and amphibia, have no amnion and are termed ''anam- 

 niotic." The reptiles, birds, and mammals which possess 

 it are termed amniotic vertebrates. 



Amphioxus: The most simply organized animal having a 

 dorsal notochord. It is classified among the Acrania in 



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