R strain (designated Ore-171) had been inbred 171 generations by brother-sister matings at the time of sampling. The hybrids were F, offspring from reciprocal crosses of and Ore-171. For the Sam-Ore hybrids Sam-269 was used as the female parent and for the Ore-Sam hybrids Ore-171 was used as the female parent. TechniquesCuZture met7aods. The standard culture medium consisting of cornmeal, agar, molasses and brewer's yeast with the addition of live yeast just before using the culture bottle was employed throughout thc experiment. Five pairs of flies of the appropriate genotypes were placed in a culture bottle and the females were permitted to lay eggs for two days, then the parents were transferred to a fresh bottle f o r 5 more days before discarding. The cultures were incubated at 26 .t 1°C. The offspring were preserved in alcohol within t v o days after emergence. Only the offspring from the first culture were used for this study.

No abstract

No abstract

No abstract

NE of the characteristic morphological features of certain of the species 0 of the Drosophiladae is the sex comb (ctenidium) on the first and in some species also the second tarsal joint of the prothoracic leg of the male but never the female. The males of Drosophila melanogcrster have a single comb of 10-12 morphologically distinct bristles (teeth) on the distal end of the first tarsal segment, but occasionally a single tooth or several teeth occur as a developmental anomaly on the other tarsal segments of the first leg or on the other legs.Five mutants are known in D. melunogmter which induce the formation of typical sex combs on the metatarsi of the posterior legs. If sex comb teeth are developed on the metatarsi of the posterior legs, it may be because the genetic factor causes differentiation of a sex comb only, and this quite independent of differentiation in the rest of the tarsus or the rest of the leg. Conversely an extra sex comb mutant may have a more profound morphogenetic effect. It may redirect the development pattern so that the posterior legs become first legs with the appropriate region of the male metatarsus differentiating a sex comb.The legs of D. melanoguster are admirably suited for morphogenetic studies