No. 579] SHORTER ARTICLES AND DISCUSSION 1 87 



But even ampelophila does not thrive when the temperature 

 reaches 100°. 



During September, 1914, I took several wild stocks of confusa 

 from the same region, and have examined many of the offspring 

 with the hopes of again finding this form but so far no unusual 

 forms have appeared. 



Roscoe R. Hyde 



MUTATIONS IN TWO SPECIES OF DROSOPHILA 



In our cultures of Drosophila. mutations have appeared re- 

 cently in two species other than Drosophila ampelophila. Both 

 mutants are characterized by abnormalities in wing venation. 

 One of them has irregular extra veins in the axillary cell, and 

 hence may be called axillary. The other is distinguished most 

 clearly by the fusion of the distal end of the second vein to the 

 costa, producing a double vein for a considerable distance, for 

 which reason it is called confluent. In each of these cases other 

 abnormal characters are associated with those mentioned, but 

 they are relatively inconspicuous. 



The mutant called axillary arose in normal stock of D. tri- 

 punctata Loew, which has been bred in the laboratory for about 

 six generations. This stock was kept in milk bottles and fed 

 on banana, but received no artificial treatment except anesthesia 

 with ether once per generation. Axillary behaves as a simple 

 Mendelian recessive when crossed with normal, and breeds true 

 in pure cultures. 



The mutant called confluent appeared in a culture of an un- 

 described species of Drosophila, referred to as "species B" by 

 one of us in a paper describing its chromosomes. 1 Confluent is 

 a dominant character (i. e., it appears in the heterozygous fly), 

 and so far as we have been able to ascertain it never occurs in 

 the homozygous condition. At least no flies homozygous for it 

 have as yet been found, although numerous matings have been 

 made which should have produced them. The original fly show- 

 ing the confluent character (a male) appeared in a stock culture, 

 all of his brothers and sisters being normal. He was hetero- 

 zygous, as shown by matings with normal females, which gave 

 15 normal and 13 confluent offspring. Seven of the latter, bred 



i" Chromosome Studies in the Diptera," I, Jour. Exp. Zool., XVII. p. 



