690 



COLLEGE ZOOLOGY 



projection; especially those on the intestinal 

 lining of vertebrates which increase the 

 absorptive surface. 



Vis'cer-a (L., internal organs). Organs en- 

 closed within the great cavities of the body, 

 especially the abdomen. 



Vi'ta-min (L. vita, life; E. amine, a chemical 

 radical). Any of a number of unrelated or- 

 ganic substances that are essential for nor- 

 mal growth and function. Vitamins are 

 necessary only in minute quantities. 



Vit're-ous (L. vitnim, glass). Glassy in ap- 

 pearance. 



Vi-vip'a-rous (L. vzvus, alive; parere, to bear). 

 Giving birth to living young that develop 

 from eggs within the body of the mother and 

 are nourished from her blood stream, as with 

 most mammals. 



Warm'-blood'ed. Animals — birds and mam- 

 mals — whose body temperature remains 

 rather constant, regardless of external tem- 

 perature. 



White blood cor'pus-cle. A colorless blood cell 

 (leucocyte). 



Wolffian ducts (After the German anatomist 

 Wolff. L. ductus, to lead). The mesonephric 

 ducts. 



X, Y chro'mo-somes. Chromosomes concerned 

 especiallv with the determination of sex. In 

 some animals the females have two X chro- 

 mosomes, and the males one X, accom- 

 panied by its unmatched mate, the Y 



chromosome. Certain others, moths for ex 

 ample, have XX males and XY females; a 

 few animals are known without a chromo' 

 some, hence having XO males and XX 

 females. 



Y chro'mo-some. See X, Y chromosomes. 



Zo'o-ge-og"ra-phy (Gr. zoion, animal; ge, earth; 

 graphein, to write). The branch of zoology 

 dealing with the geographic distribution of 

 animals. 



Zo'oid (Gr. goiozides, like an animal). (1) 

 one of the members of a hydroid or 

 siphonophore colony. Often in a restricted 

 sense, a particular kind of individual, as 

 hydranth or gonangium. (2) A subordinate 

 individual formed by transverse fission in 

 such forms as the planaria. 



Zo-oro-gy (Gr. zoion, animal, living being; 

 logos, study). The science of animal life. 

 Coordinate with botany as a division of 

 biolog\-. 



Zyg'a-poph"y-sis (Gr. zygon, yoke; N.L. 

 apophysis, offshoot). One of the four pro- 

 jections, two anterior and two posterior, ex- 

 tending from the neural arch of a vertebra. 

 Those of the posterior pair articulate with 

 the anterior of the vertebra next behind. 



Zy'gote (Gr. zygotos, united). The cell which 

 results from the fertilization of one gamete 

 by another. The product of the union of two 

 gametes of any type, not necessarily an egg 

 and sperm. 



