374 PRINCIPLES OF ANIMAL BIOLOGY 



Carpometacarpus (kar' po met a kar' pus). A compound bone in the wing of a bird, 



formed by the union of several of the metacarpals and carpals. 

 Cartilage. A flexible, somewhat translucent tissue composed of cells imbedded in a 



matrix, found on the ends of bones at joints and in other situations. 

 Cast. A mass of rock formed within a cavity, as the cavity of a shell or of a mold 



formerly occupied by an animal. 

 Catabolism {ka tab' o liz'm). The aggregate of destructive processes comprised in 



metabolism. 

 Catalase. An enzyme which liberates oxygen from hydrogen peroxide. 

 Catalyst {kat' a list). A substance which brings about a reaction but is not consumed 



in that reaction. It probably often participates in the reaction but is promptly 



reformed. 

 Caudal. Belonging to the tail. 



Caudata. Aii order of Amphibia comprising forms with tails (salamanders, newts). 

 Cell. A mass of protoplasm containing a nucleus or nuclear material. 

 Cell doctrine. See cell theory. 



Cell inclusions. Nonliving objects enclosed in cells. 



Cell membrane. A thin sheet either of differentiated protoplasm, or of some sub- 

 stance produced by protoplasm, surrounding a cell. 

 Cell theory. The theory that all animals and plants are composed of similar units 



of structure called cells. The theory is now so well established as to be inore 



properly called the cell doctrine, and other features concerning physiology, 



development, etc., may be included in it. 

 Cellulose (sel' u lose). The substance, one of the carbohydrates, of which the cell 



walls of plants are commonly composed. 

 Cell wall. A nonliving structure secreted by a cell around itself. It is commonly 



composed of cellulose or chitin. 

 Cement. A binding material in the composition of teeth. 

 Cenozoic (se' no zo' ik). Pertaining to the most recent geological era. 

 Central nervous system. The brain and spinal cord. 

 Centriole. A minute body in the center of a centrosphere, and located at the end of 



the spindle of many dividing cells. 

 Centrolecithal {sen' tro les' i thai). Having the yolk in a central position, surrounded 



by protoplasm at the surface; said of eggs. 

 Centrosome {sen' tro some). A minute body often present in a cell, usually near the 



nucleus in a centrosphere, related in some way to the process of cell division. 



By many writers the name is used interchangeably with centriole. 

 Centrosphere {sen' tro sfeer). A differentiated portion of the cytosome of a cell, 



usually near the nucleus, and typically containing a centrosome or centriole. 

 Centrum. The massive portion of a vertebra ventral to the neural canal in which 



the spinal cord rests. 

 Cephalochorda {sef a lo kor' da). A subphylum of Chordata, comprising the species 



of Amphioxus. For definition see Chap. 19. 

 Cephalopod {sef a lo pod). One of the group Cephalopoda, to which the cuttlefishes, 



squids, and nautili belong. 

 Cephalopoda {scf a lop' o da). A class of Mollusca, comprising the octopi, squids, 



cuttlefishes, and nautili, animals in which the foot is developed into a headlike 



structiu-e with eyes and a circle of arms. 

 Cephalothorax {scf a lo tho' raks). A fused head and thorax, found in crayfishes and 



their allies. 

 Ceratite {ser' a tite). An extinct cephalopod having a coiled shell and crooked 



sutures; named from the genus Ceratites. 



