Bristle Pattern in Scute Stocks of Drosophila melanogaster

Counts of scutellar bristle number in four stocks of flies homozygous for scute are recorded together with details of the position of each bristle. It is concluded from the distribution of the bristles that the formation of a bristle at one site is not entirely independent of the formation of a bristle at another site or of the total number of bristles formed. That is to say, total number of bristles is determined and is primary to the formation of a bristle at any given site. These findings are discussed with reference to Robertson's view of bristle formation.