92 



The Journal of Heredity 



germ-cell. The word is gradually fall- 

 ing into disuse, and "factor" taking its 

 place. 



Dominance, in Mcndelian hybrids the 

 capacity of a character, which is de- 

 rived from only one of the two generat- 

 ing gametes, to develop to an extent 

 nearly or quite equal to that exhibited 

 by an individual which has derived the 

 same character from both of the gener- 

 ating gametes. In the absence of dom- 

 inance, the given character of the hybrid 

 usually presents a "blend" or interme- 

 diate condition between the two parents. 

 Dysgenic, tending to impair the racial 

 qualities of future generations; the 

 opposite of eugenic. 



Endogamy, a custom of primitive 

 peoples, in compliance with which a 

 man must choose his wife from his own 

 group (tribe, clan, etc.). 



Eugenic, tending to improve the racial 

 qualities of future generations, either 

 physical or mental. 



Euthenic, tending to produce better 

 conditions for people to live in (but nor 

 tending to produce people who can hand 

 on improvement by heredity). 



Evolution (organic), the progressive 

 change of living forms, usually asso- 

 ciated with the development of com- 

 plex from simple forms. 



Exogamy, a custom of primitive 

 peoples which requires a man to choose 

 a wife from some other group (tribe, 

 clan, etc.) than his own. 



Factor, a name given to the hypo- 

 thetical something, the independently 

 inheritable clement in the germ-cell, 

 whose presence is necessary to the de- 

 velopment of a certain inherited char- 

 acter or characters, or contributes with 

 other factors to the development of a 

 character. "Gene" and "determiner" 

 are sometimes used as synon\Tns of 

 factor. 



Feeblemindness, a condition in which 

 mental development is retarded or in- 

 complete. It is a relative term, since 

 an individual who would be feeble- 

 minded in one society might be normal 

 or even bright in another. The cus- 

 tomary criterion is the inability of the 

 individual, because of mental defect 

 existing from an early age, to compete 

 on equal terms with his nonnal fellows, 



or to manage himself or his affairs with 

 ordinary prudence. American students 

 usually distinguish three grades of men- 

 tal defect: Idiots are those who are 

 unable to take care of themselves, even 

 to the extent of guarding against com- 

 mon physical danger or satisying physi- 

 cal needs. Their mentality does not 

 progress beyond that of a normal two- 

 year-old child. Imbeciles can care for 

 themselves after a fashion, but are un- 

 able to earn their living. Their mental 

 ages range from three to seven years 

 inclusive. Morons, who correspond to 

 the common acceptation of the term 

 feebleminded, "can under proper direc- 

 tion become more or less self-supporting 

 but they are as a rule incapable of 

 undertaking affairs which demand judg- 

 ment or involve unrestricted competition 

 with normal individuals. Their in- 

 telligence ranges with that of normal 

 children from seven to twelve years of 

 age." There is necessarily a consider- 

 able border-line, but any adult whose 

 intelligence is beyond that of the 

 normal twelve-year-old child is usually 

 considered to be not feebleminded. 



Gamete, a mature germ-cell, in ani- 

 mals an ovum or spermatozoon. 



Genetics for a long time meant the 

 study of evolution by experimental 

 breeding and was often synonymous 

 with Alendelism. It is gradually re- 

 turning to its broader, original meaning 

 of the study of heredity. This broader 

 meaning is preferable. 



Germinal, due to something present 

 in the germ-cell. A trait is gemiinal 

 when its basis is inherited, as eye-color, 

 and when it develops with nothing 

 more than the standard environment; 

 remaining relatively constant from one 

 generation to another, except as in- 

 fluenced by reproduction. 



Germ-plasm, mature germ-cells and 

 the living material from which they are 

 produced. 



Haemophilia, an inability of the blood 

 to clot. It thus becomes impossible 

 to stop the flow of blood from a clot, 

 and one who has inherited haemophilia 

 usually dies sooner or later from hem- 

 orrhage. 



Heredity is usually considered from 

 the outside, when it may properly be 



