326 GLOSSARY 



choanocyte, ko' a no sit (Gr. choane, a funnel; kutos, a cavity), a collared 



cell of the sponge. 

 chromatin, krd'ma tin (Gr. chroma, color), the deeply staining substance 



of the nuclear network and of the chromosomes, consisting of nuclein. 

 Chromosome, kro'mo som (Gr. chroma, color; soma, body), the deeply 



staining bodies into which the chromatic nuclear network resolves itself 



during mitosis. 

 Chromotropism, kro nibt'ropizm (Gr. chroma, color; trope, a turning), the 



reaction of an animal to. color. 

 cilium, sit i um (L. cilium, an eyelid with the hairs growing on it), a minute 



hairlike process of a cell. 

 Class, kl'as (L. classis, an assembly of people), a number of animals regarded 



as a collective unit because of the presence of certain common characters. 

 cleavage, kle'vdj, th^mvision of the fertilized egg. 

 clitellum, klitel'um (L. clitellx, a pack saddle), a glandular ring around 



the body of the earthworm. 

 cnidoblast, ni'do blast (Gr. knide, a nettle ; blastos, a bud), a cell in which a 



nematocyst is developed. . 

 cnidocil, m'do sil(Gr. knide, a nettle; L. ciliiim, an eyelid), a stiff hairlike 



process projecting from a cnidoblast. 

 coagulate, ko ag'ti Idt (L. coagulare, curdle), change from a fluid into a 



curdlike or thickened mass. 

 Ccelentera, se len'te r'd (Gr. koilos, hollow; enteron, intestine), a phylum of 



animals with a single body cavity which opens by a single orifice, the 



mouth. 

 CCelom, se'lom (Gr. koilos, hollow), the true body cavity, lying between the 



digestive tract and the body wall, and lined with epithelium, 

 coelomate, se Id' mat (Gr. koilos, hollow), having a coelom. 

 commensalism, ko men'salizm (L. com, together; mensa, table), the living 



together of two species of animals or plants, but neither at the expense of 



the other. 



conjugation, konjo gd'shon (L. conjugatum, to unite), a temporary or perma- 

 nent union of two cells for reproduction. 



contractility, kon traktil'i ti (L. contractus, a drawing together), the prop- 

 erty or force by which bodies shrink or contract. 

 copulation, kop n Id'shon (L. copulare, unite), the active transmission of 



sperm from the male to the female. 



cortical, kbr'ti kal (L. cortex, bark, rind), belonging to the external covering, 

 cuticle, ku'ti kl (L. cuticula, dim. of cutis, the skin), the outermost covering 



of the body of certain animals. 

 cyclosis, st kid' sis (Gr. kuklos, a circle), applied to currents within the bodies 



o* Protozoa 



