GLOSSARY 



CUTICLE (CUTICULA), firm layer outside the hy- 



poderrais which protects the insect body 



and serves as a support for the internal 



organs. Formed from chitin. 



DELETION, the loss of a chromosomal segment. 



DIAKINESIS, the final stages of meiotic pro- 

 phase in whi-ch the homologous chromosomes 

 are in intimate association. 



DIFFERENTIATOR, a factor that prevents somatic 

 overlapping of traits. 



DIPLOID, referring to the double set of chromo- 

 somes, as found in the body cells of ani- 

 mals and the sporophyte generation of 

 plants, as distinguished from the single 

 (haploid) set, found in the mature repro- 

 ductive cells. 



DISPERMIC, an egg fertilized by two sperms. 



DOMINANT, a character which appears as the re- 

 sult of the presence of either a single or 

 a double dose of a particular gene, as 

 contrasted with the recessive, which de- 

 velops only when both members of a pair of 

 genes are alike. Applied also to the genes. 



DOUBLES, double breaks in chromatids that occur 

 during diakinesis, and the resulting geno- 

 types, and the individuals possessing them. 



DYAD, each of the two chromatids formed from a 

 single chromosome during meiosis. 



E 



ECLOSION, emergence of adult insect from the 

 pupal case. 



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