588 GLOSSARY 



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



basement membrane. A thin connective tissue membrane to which epitheUal 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' thSs). 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' ml Si). Consisting of two names; in the accepted nomenclature these 



are the names of the genus and the species. 

 bio (bi' 6). G.; life, related to life. 

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



things have arisen only from preexisting living things. 

 biogenetic (bi o je n6t' Ik) law. The doctrine that in the embryogeny 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 o' ta). A collective term for the animals and plants of a given area; adj., 



biotic (bi 5t' Ik). 

 biparental. Involving two parents. 



biradial symmetry. A combination of radial and bilateral symmetry, 

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

 bivalent (bi va' Ignt). 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' t6 sel). The cavity of a blastula; the cleavage, or segmentation, 



cavity. 

 blastoderm (bias' t6 durm). The sheet of cells surrounding the cleavage cavity in a 



blastula; adj., blastodermic (bias t6 dur' mik) or blastodermal. 

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

 blastopore. The opening into the archenteron. 

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



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

 blepharoplast (blgf a ro plast). A granule in a cell from which a flagellum or cihum 



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 (br6n' kus). An air passage within a lung. 

 Brown, Robert. Scottish botanist; 1773-1858. 



Bruner (broo' ner), Lawrence. American entomologist; 1856-1937. 

 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. 



