560 GLOSSARY 



Baker, Frank C. American zoologist, at University of Illinois; 1867- . 



basement membrane. A thin connective tissue membrane to which epithelial cells 



are attached. 

 behavior. The sum total of an animal's movements in response to changing environ- 

 mental conditions or to changes within the organism. 

 benthos (b6n' thos). The life of the sea bottom, especially of the deep seas; it does 



not properly apply to the littoral fauna of shallow water; adj., benthal. 

 bi- (bi). L.; two, or twice. 



Bichat (be sha'), Marie F. X. French anatomist and physiologist; 1771-1802. 

 bilateral symmetry. Symmetry which involves the possibility of dividing a body 



only into two parts, which are mirror images of each other. 

 bile. The secretion of the liver in vertebrates. 



binary (bl' na ri) fission. The division of an organism into two similar organisms. 

 binomial (bi no' mi al). Consisting of two names; in the accepted nomenclature these 



are the names of the genus and the species. 

 bio (bi' o). G.; life, related to life. 

 biogenesis (bi o jen' e sis). The conception that since the beginning of life living 



things have arisen only from preexisting living things. 

 biogenetic (bi 6 je nH' ik) law. The doctrine that in the embrj^ogeny of any higher 



animal there appear stages or conditions similar to those which were present in 



the adults of lower types ancestral to it. 

 biota (bi 5' ta). A collective term for the animals and plants of a given area; adj., 



biotic (bi 6t' Ik). 

 biparental. Involving two parents. 



biradial symmetry. A combination of radial and bilateral symmetry, 

 biramous (bi ra' miis). Having two branches, 

 bivalent (bi va' lent). Having the value of two. 

 bladder. A membranous sac; the air bladder contains gases, the gall bladder serves 



for the temporary storage of bile, and the urinary bladder serves for the accumu- 

 lation of urine. 

 blast (blast). G.; germ, relating to the early stages of the embryo. 

 blastocoel (bias' to sel). The cavity of a blastula; the cleavage, or segmentation, 



cavity, 

 blastoderm (bias' to dtirm). The sheet of cells surrounding the cleavage cavity in a 



blastula; adj., blastodermic (bias to diir' mik) or blastodermal, 

 blastomere (bias' to mer). A cell of the blastoderm. 

 blastopore. The opening into the archenteron. 

 blastula (bias' tii hi.). An embryo in the stage when it is composed of a blastoderm 



inclosing a blastocoel, like a hollow ball of cells; adj., blastular. 

 blepharoplast (bl6f' a ro plast). A granule in a cell from which a flagellum or cilium 



arises, 

 brachio (brak' I 6). G.; arm. 

 brachy (brak' i). G.; short. 



branch! (bran' kl). L.; gill. Branchial (bran' kl al). Pertaining to gills, 

 breathing. The passage of air into and out of a cavity in an animal body leading to 



the interchange of gases through the wall of the cavity, an interchange which is 



respiration. 

 bronchus (bron' kiis). An air passage within a lung. 

 Brown, Robert. Scottish botanist; 1773-1858. 

 Bruner (broo' ner), Lawrence. American entomologist; 1856- . 

 buccal (buk' al). Pertaining to the mouth. 

 budding. The production of a young animal from the body of a parent and its 



separation, while still small, from the parent, after which it is able to live inde- 

 pendently. 



