236 



/'// YSIOLOGH 'AL OENETICS 



are reporting only such parts of the discussion as have to do with 

 the production of the specific bristle pattern by the action of 

 genes, whatever they are. The school of Serebrovsky (Dubinin, 

 Lewit, Agol, etc.) which has furnished most of the data has used 

 them only in an attempt to analyze the gene itself (see page 295). 



FlQ. 47. — Location of bristles of Drosophila mclanogaster. aor, mor, par, 

 anterior, middle, posterior orbitals; oc, ocellar; pv, post vertical; iv, ov, inner, 

 outer verticals; uh, Ih, upper and lower humerals; anp, pnp, anterior and posterior 

 notopleurals; ps, presutural; asa, psa, anterior, posterior supra-alar; apa, ppa, 

 anterior, posterior postalar; adc, pdc, anterior and posterior dorsocentrals; asc, 

 psc, anterior, posterior scutellars. (From Plunk ett, 1926, Jour. Exp. Zool. 46.) 



Sturtevant and Sehultz (1931) and Goldschmidt (19316) tried to 

 look at the case from the standpoint of pattern formation, and 

 Child (1935, 1936) has recently attacked the problem also. 



The work in question is based upon the idea that these different 

 alleles produce a definite pattern of bristles by removing specific 

 individual bristles. If this is done in an orderly way, the 

 phenotypes of the different alleles may be arranged in a corre- 

 sponding seriation. Figure 47 represents the bristles in question 

 on head, thorax, and scutcllum of Drosophila, with their respec- 



