Appendix 813 



II. GLOSSARY, BIOLOGIC PRINCIPLES, AND THEORIES 



One of the most important contributions which the science of biology can 

 make to the individual student is the imparting of a knowledge of the general 

 principles and theories which underlie living organisms and their varied activi- 

 ties. Many of the detailed structures and functions of living organisms may be 

 forgotten when the knowledge of the general principles will remain and con- 

 tinue to be a source of value and satisfaction. An attempt is made to summarize 

 briefly the more important principles and theories. In some instances, clarity 

 and completeness are sacrificed for the sake of necessary brevity. In cases where 

 the consideration is insufficient, the reader is directed to the proper part of the 

 text or to additional references. 



The pronunciation, based on Webster's New International Dictionary, is given 

 and the syllable to be emphasized is marked by '. The derivations of the terms 

 are included not only for a better understanding of the term, but to enable the 

 student to use these derivations in an attempt to explain the meaning of other 

 words with which he may not be familiar. Those derived from Greek are desig- 

 nated by Gr., those from Latin by L., those from Anglo-Saxon by A.S., and those 

 from French by Fr, 



A 



Abdomen (ab-do'men) (L. abdomen, belly), the part of the animal, posterior to 



the thorax. 

 Abductor (ab -duk' ter) (L. ab, away; duco, to lead), leading away from the 



center or median line (contrast with adductor). 

 Abiogenesis (ab i o -jen' e sis) (Gr. a, not; bios, life; genesis, to create), the 



former theory that all living matter arose spontaneously from nonliving 



matter (same as spontaneous generation). 

 Aboral (ab -o' ral) (L. ab, from; os, mouth), opposite the mouth. 

 Abortion (a -bor' shun) (L. abortare, to miscarry), premature birth or incom- 

 pletely formed structure. 

 Absorption (ab -sorp' shun) (L. ab, away; sorbere, to suck or remove), the taking 



up of substances or their passage through the walls of cells or vessels. 

 Acclimation (ak li -ma' shun) (L. ad, toward; klimat, region), the process of be- 

 coming accustomed or habituated to environmental conditions which are 



not native. 

 Accommodation (a kom o -da' shun) (L. ad, to; commodus, fit), the ability of the 



eye to adjust to objects near and far. 

 Accretion (a-kre'shun) (L. accrescere, to increase), increasing in size by adding 



deposits to the surface (contrast with intussusception). 

 Acetabulum (as e -tab' u lum) (L. acetabulum, saucer-shaped), a cavity on each 



side of the pelvic bone into which the femur fits. 

 Achromatic figure (a kro -mat' ik) (Gr. a, not; chroma, color), the nonstaining 



part of the nucleus. 

 Acoelomate (a -se' lo mat) (Gr. a, without; koilos, hollow), without a hollow, 



true, body cavity or coelom. 

 Acquired characters, modifications of structures or functions acquired by the 



body plasm through the changes in environment or functions (contrast 



with mutation). 



