GLOSSARY 165 



blastula. A hollow sphere of cells produced by the develop- 

 ment of the egg. 



body cavity. Coelom; the cavity between the digestive 

 tube and the body wall. 



brachial. Pertaining to the arms. 



branchial. Pertaining to the gills. 



buccal groove. In infusoria the groove leading to the mouth. 



caecum. A tube or sac open at one end only; usually applied 

 to appendages of the digestive tract. 



calcareous. Composed of lime or calcium carbonate. 



calciferous. Esophageal glands in the earthworm contain- 

 ing calcium carbonate. 



capsule. A little case. In hydroids the cavity of a sting- 

 ing cell which contains the poison. 



carapace. A shell or shield covering the head and thorax 

 of Crustacea. 



cell. One of the structural units of a living body; a mass 

 of protoplasm containing a nucleus. 



centrosome. The central body or region of an aster in 

 mitosis. 



cephalothorax. The region of the body composed of the 

 fused head and thorax. 



cerebral. Pertaining to the cerebrum or brain; in inverte- 

 brates cerebral ganglia or brain. 



chela. The pincer-like claw of Crustacea and other arthro- 

 pods. 



cbitin. The horny material forming the covering of insects 

 and certain other animals. 



chlorogog. Gland cells surrounding the stomach-intestine 

 of the earthworm. 



