GLOSSARY 911 



Gametes (gam'ets). (See Germ cells.) 



Gametogenesis (gam e t6 jen'e sis), the series of cell divisions in the develop- 

 ment of germ cells. 



Ganglion (gang'lion), a group of nerve cell bodies outside the central nervous 

 system. 



Ganoid scale (gan'oid), rhombic in shape, composed of an inner layer of bone 

 and outer layer of enamel. 



Gastrula (gas'trdo la), the two-layered stage in the development of an embryo. 



Genes (jenz), the units of material which function in the transmission of 

 characters in heredity. 



Genetics (jenet'iks), the science that treats of variation, resemblances, and 

 their inheritance from parent to offspring. 



Genotype (jen'otip), the genetic constitution of genetically identical or- 

 ganisms. 



Genus (je'nus), pi. Genera (jen'era), a division of the classification, a sub- 

 division of a family, and is divided into species. 



Geotropism (je ot'ro piz'm), response of an organism to gravity. 



Germ cells (jerm) (gametes), cells specialized for reproduction. 



Germ layer (jerm), one of the primary cell layers in an embryo. 



Germ plasm (jerm plazm), the hereditary material of an organism, the 

 chromatin. 



Gills (gils), (pharyngeal clefts), a series of paired slits in the wall of the 

 pharynx and liody. 



Gonads (gon'ads), reproductive organs. 



Gonophore (gon'ofor), a reproductive individual which bears gonads, as in 

 Hydroids. 



GlocMdiiim (gl6 kid'i iim'i, the larva of a fresh-water clam. 



Glomerulus (gl6 mer'ulus), a body of capillaries enclosed at the end of each 

 kidney tubule of the mesonephric and metanephric types of kidneys. 



Glycerol (glis'erol), one of the alcohols which enters into the composition 

 of fats; glycerin. 



Glycogen (gli'ko jen), a form of carbohydrate food material as formed and 

 stored by the liver. 



Habitat (hab'itat), the place or area in which an animal or species lives. 



Haploid (hap'loid), the reduced or half number of chromosomes of the mature 

 germ cells. 



Heliotroplsm (he li ot'ro piz'm), a response of an organism to light. 



Hemoglobin (he mo glo'bin), a protein pigment substance of the blood which is 

 capable of absorbing oxygen and is red when coml)ined with it. 



Hemolysis (he mol'i sis), disintegration of red blood corpuscles. 



Hepatic (hepat'ik), pertaining to the liver. 



Herbivorous (hur biv'6 riis), herb or plant-eating animals. 



Hermaphoditlc (hur maf ro dit'ik) (monoecious), having both male and fe- 

 male germ cells produced in one individual. 



Heterozygote (het er 6 zi'got), an organism which is carrying sets of unlike 

 characters in its genetical constitution. 



Hibernation (hi ber na'shiin), the cessation of activity or dormancy of an an- 

 imal during the winter season. 



Histogenesis (his to jen'e sis), the development and differentiation of tissue 

 cells. 



Histology (histol'oji), the science that treats of the microscopic structure 

 of the various parts of the animal body. 



Holoblastic (hoi u blas'tik), having the tj-pe of egg structure in which cleavage 

 divides the entire egg. 



Holozoic (holozo'ik), the animal nutrition, the ingestion and digestion of 

 organic material. 



Homoiothermal (ho moi'6 thur mal), having a temperature regulation. 



