Glossary 



379 



glands of internal secretion, or 

 in general tissues, and carried 

 by the blood and lymph over the 

 body generally, to influence the 

 growth or functioning of other 

 tissues. Hormones is another 

 name given to these substances. 



CHEMOTROPIC. Pertaining to the 

 reaction of organisms to chem- 

 ical stimuli. 



CHROMATIN. The finely granular 

 substance most distinctive of the 

 cell-nucleus. Its name comes 

 from the readiness with which 

 it is colored by many dye-stuffs. 



CHROMATOPHORES. Pigment-bear- 

 ing sacs, often single cells, in 

 plants and animals. It is by 

 means of these that the rapid 

 color changes in the skin of 

 many animals are accomplished. 



CHROMIDOSOMES. One of the many 

 names given to minute specially 

 stainable bodies in the cytoplasm 

 of many cells. 



CHROMOSOMES. The more or less 

 definite bodies of the cell-nu- 

 cleus into which the chromatin 

 granules are grouped. Their 

 constancy of structure and rela- 

 tion to hereditary characters 

 have given them great promi- 

 nence in much of recent biolog- 

 ical theory. 



CHROMOPHIL. Any body in the liv- 

 ing organism that has an avidity 

 for staining reagents. 



Coccus. In the classification of 

 bacteria according to their 

 shapes, those which are spherical 

 are called cocci. 



COELENTERATA. A group of ani- 

 mals that have a digestive cav- 

 ity, but nothing corresponding 

 to the abdominal cavity; also 

 called radiata from the radial 

 arrangement of the body. 



CORTICAL. Pertaining to the cor- 

 tex, or outer layer of an organ, 

 as of the brain, bark of the tree, 

 &c. 



CRETIN. An individual aifected 



with cretinous disease, a disease 

 characterized by certain bodily 

 deformities and mental impair- 

 ments. The malady frequently 

 accompanies goitre, and is now 

 considered due to deficiency in 

 secretion of the thyroid gland. 

 CRUSTACEA. A class of inverte- 

 brate animals belonging to the 

 great phylum arthropoda, briefly 

 characterized by their exoskele- 

 ton and paired jointed appen- 



CYTOLOGY. Science of the cell. 



CYTOPLASM. Substance of the cell- 

 body, as opposed to the cell-nu- 

 cleus. 



DETERMINANTS. That particular 

 class of imaginary ultimate vital 

 units by which the development 

 of hereditary attributes is deter- 

 mined. They were invented by 

 Weismann, and were conceived 

 to constitute the germ-plasm, 

 and to be located primarily in 

 the chromosomes of the egg and 

 sperm. In later speculation de- 

 terminer is used more frequently 

 than determinant on some ac- 

 count that is not clear. 



DIATOMS. An immense group of 

 aquatic, unicellular algae espe- 

 cially characterized by their 

 firm, box-like, regularly-shaped, 

 chitinous shell. 



DINOFLAGELLATES. Literally or- 

 ganisms which are two-lashed, 

 . owing to the two flagella pos- 

 sessed by most of the species. 

 A group of aquatic unicellular 

 organisms almost as numerous as 

 the diatoms. The photo-synthe- 

 sizing power of living substance 

 possessed by these two groups, 

 and their enormous abundance 

 at and near the surface of the 

 bodies of water in which they 

 live, make them fundamentally 

 important for all the life of the 

 waters of the earth. 



DISTAL. A common anatomical 

 term signifying away from a 



