GLOSSARY-INDEX 393 



chlorogogen cells. The cells which fill the typhlosole and cover the intes- 

 tine in the earthworm, 169. 



chlorophyll (Gr. chloros = green + phyllon = leaf). The green coloring 

 material in plants which enables them to carry on photosynthesis, 93, 

 117, 131, 218. 



chlorophyll bodies, 37. 



chloroplasts (Gr. chloros = green + plastos = molded). Cells which pro- 

 duce chlorophyll, 117. 



Chordata (Gr. chorde = a string). Animals possessing a notochord, includ- 

 ing all Vertebrata, 378. 



choroid (Gr. chorion = skin). The pigment-holding layer of the eyeball, 

 inside the sclerotic coat, 196. 



choroid coat, of the eye, 196. 



choroid plexus. A membrane full of blood vessels covering certain cavities 

 in. the brain, 193. 



chromatin (Gr. chroma = color). The material in the nucleus holding the 

 characteristic features of cell life and concerned in inheritance, 33, 259. 



chromatophore (Gr. chroma = color + pherein = to bear). A pigment- 

 bearing cell. 



chromidial units, 50. 



chromogenic. Pigment-producing. 



chromosomes (Gr. chroma = color + soma = body). The threads of 

 chromatin formed preliminary to cell division; the number is constant 

 in each species of organism, 85. 



chyle. The completely digested food in the intestine. 



cilia (Lat. cilium = an eyelash). Vibratile processes of protoplasm from 

 the free surface of cells, 60, 218. 



circulation, 138, 206, 309; of earthworm, 158; of frog, 187, 205; of Hydra, 

 146. 



Cladonia, 229. 



class. A group of closely related orders, 373. 



classification of organisms, 370, 375; significance of, 374. 



clavicle, 182. 



cleavage. The division of the egg into cells, 281. 



clitellum (Lat. clitellce = a saddle). A band of swollen segments in the 

 earthworm, between the 28th and 35th segments, 157. 



cloacal aperture (Lat. cloaca = sewer). The common opening of the intes- 

 tine and the urogenital organs, 175, 186. 



cloacal chamber, 284. 



cnidoblast (Gr. cnide = thistle + blastos = a sprout). The ectodermal cells 

 in Ccelenterata which produce the nematocysts. 



cnidocil, 144. 



