xxiv GLOSSAEY OF TECHNICAL TERMS 



GASTRULATION (Gr. yao-nj/o, belly), the process by which the gastrula 



is formed. 



GENUS (Gr. yeVo?, race), a group of closely related species. 

 GERM CELLS, single cells which are capable of developing into new 



individuals (usually after conjugating in pairs). 

 GERMINAL DISK, a speck of active protoplasm in a heavily-yolked 



egg, from which the embryo develops. 

 GERM LAYER, one of the fundamental layers of cells which appear 



at an early stage of development in multicellular animals. 

 (JERM PLASM, that part of the protoplasm of the germ cell 



(probably the chromatin substance of the nucleus), which 



is supposed to be the bearer of inheritable tendencies. 

 GLAND (Lat. glans, nut), an organ which secretes or excretes some 



special substance. 



GLIADIN (Gr. yXota, glue), a proteid substance occurring in flour. 

 GLUCOSE (Gr. yAvKvs, sweet), a carbohydrate, also known as grape 



sugar. 

 GLUTININ (Lat. gluten, glue), a proteid substance occurring in 



flour. 

 GONAD (Gr. yoVos, reproduction), the organ (ovary or testis) in 



which the germ cells appear. 

 GONODUCT (Gr. yoVoj, reproduction ; Lat. ductus, conduit), a duct 



or tube through which germ cells pass to the exterior of the 



body. 



GONOPHORE (Gr. yoVos, reproduction ; <f>opvs, bearer), an indivi- 

 dual which bears gonads or reproductive organs (in Hydroids). 

 GONOTHECA (Gr. yoyos, reproduction ; #77*77, box), a hollow skeletal 



structure containing gonophores (in Hydroids). 

 GYNCECIUM (Gr. <yu^, woman; cuaW, dwelling place), the "female " 



organs of a flower, consisting of ovary, style and stigma, 



formed from modified leaves known as carpels. 

 H^MATID (Gr. at/xa, blood), a red blood corpuscle. 

 H^MATOCHROME (Gr. atjua, blood ; xP<M a > colour), a red modifi- 

 cation of chlorophyll, found in Haematococcus. 

 HEMOGLOBIN (Gr. atjua, blood ; globulin, a proteid), the red 



colouring matter of blood. 

 HERMAPHRODITE (Gr. 'Ep/xr??, 'A(/>podir?7, a god and goddess), 



bearing both male and female reproductive organs. 

 HETEROGENY (Gr. erepoy, different ; rt. ytv-, birth), an alternation 



of normal sexual with parthenogenetic individuals in the life 



cycle. 



