Glossary 673 



Autosome — any chromosome other than the sex chromosomes. 



Axial skeleton — the portion of the skeleton comprising the skull, backbone, ribs, 



and sternum. 

 Axolotl— a salamander that ordinarily does not metamorphose, but breeds in a 



larval condition. 

 Axon — a nerve cell process that conducts impulses away from the cell body. 



B 



Belly — the main portion of a muscle ; the abdomen. 



Benthos — organisms living at the bottom of an ocean or lake. 



Bilateral symmetry — the condition in which the right and left sides are mirror 

 images of one another. 



Bile — a secretion of the liver. 



Binomial nomenclature — a system of naming animals in which each species re- 

 ceives two names, the first being the generic, the second the specific. 



Biome — in ecology, the largest recognized unit. 



Blastocoel — the cavity of the blastula. 



Blastomere — any cell in the early stages of cleavage. 



Blastula — a stage in early embryology in which the cells are grouped to form 

 a hollow ball. 



Bolus — a rounded mass such as chewed food. 



Bone — a unit of the skeleton; tissue that composes skeleton. 



Brain — a large mass of nerve tissue at the anterior end of the body. 



Bronchus — a subdivision of the trachea. 



Budding — a method of asexual reproduction. 



Buffer — a substance which tends to preserve the pH of a solution when acids 

 or bases are added. 



Bursa — a saclike cavity. 



C 



Caecum — a blind pouch. 



Canalicule — a minute canal. 



Capillary— a small, thin-walled vessel, especially the smallest vessels of the 



blood system. 

 Carbohydrates — a class of foods which includes the sugars and starches. 

 Cardiac — pertaining to the heart. 



Carnivorous — preying or feeding upon live animal material. 

 Cartilage — a type of connective tissue. 

 Catabolism — the destructive phase of metabolism. 

 Cation — a positively charged particle. 

 Caudal — pertaining to the tail. 

 Cell — unit of structure and function of animals. 

 Centrosome — a minute structure found in the cytoplasm. 

 Cephalic — pertaining to the head. 

 Cerebellum — part of the vertebrate brain. 

 Cerebrum — part of the vertebrate brain. 

 Chiasma — crossing. 



