506 GLOSSARY 



DI-HY'-BRID. The offspring of parents differing in two char- 

 acters. 



DI-O-NAE'-A. An insect-catching plant, the "Venus Fly-trap." 



DIP'-LOID. The full number of chromosomes found in the ferti- 

 lized egg and in all cells derived from this, except the 

 mature germ cells. 



DOMINANT CHARACTER. A character inherited from one parent 

 which develops to the exclusion of a contrasting character 

 of the other parent. 



DROS-OPH'-I-LA. A genus of fruit-flies. 



DU'-PLEX FACTORS or CHARACTER. A condition where the de- 

 terminers for a character are derived from both parents. 



E-CHI'-NO-DERMS. A phylum of marine animals which includes 

 star-fishes and sea-urchins. 



E-COL'-O-GY. The science which deals with the relations of 

 organisms to one another and to environment. 



EC'-TO-DERM. The outer layer of cells of an embryo which 

 gives rise to epidermis, sense organs and nervous system. 



EM-BRY-OG'-E-NY. Early development of an egg leading to 

 the formation of an embryo. 



EN'-DO-DEHM. The inner layer of cells of an embryo, which 

 gives rise to the digestive cells of the alimentary system. 



EP-I-GEN'E-SIS. The doctrine that the germ is simple and 

 homogeneous and that development consists in the for- 

 mation of complex parts from the simple germ. 



EQUATION-DIVISION. An ordinary nuclear division in which 

 each chromosome divides equally. 



EU-GEN'-ICS. The system of imp roving 'races by good breeding. 



EU-THEN'-ICS. The system of improving individuals by good 

 environment. 



EX-O-GAS'-TRU-LA. A gastrula with the endoderm turned out 

 instead of in. 



FACTOR. A specific germinal cause of a developed character. 



FERTILIZATION. The union of male and female sex cells. 



FLA-GEL'-LUM. A vibratile thread of protoplasm which serves 

 as an organ of locomotion. 



FLUCTUATIONS. Variations which are not inherited. 



