CLOSELY LINKED LETHALS IN DROSOPHILA” ETC. 459; 
tion and drawing given by STURTEVANT 1918 1). Among other somatic 
characteristics of this mutant is also a very typical and constant 
wing alteration. The wings are held out from the body and are 
bent back near the base. 
I had at the time, and have it still, a line of this stock in which 
another III chromosome lethal, closely linked to Dichaete, had 
arisen by independent mutation 2). Since it was on the occasion 
mentioned my intention only to use the Dichaete flies for the: 
purpose of demonstrating a striking mutant wing alteration, I had 
brought a culture belonging to this special line with me to Copen- 
hagen. This stock has namely for the purpose mentioned the advan- 
tage that the large majority of the flies, and not only two thirds, 
are heterozygous Dichaete and accordingly show the wing altera- 
tion. This is the result of the action of the second lethal present, 
which kills off all the normal winged individuals except the few 
cross-over flies resulting from a crossing over between Dichaete- 
and the additional lethal. 
This culture was the one Dr. WINGE obtained'from me. Its. 
double heterozygous constitution was very well known beforehand. 
Both in genetic and somatic respects the Dichaete mutant is very 
different from, and has nothing to do with the recessive mutant 
called spread, the only thing the two have in common being that 
they both belong to the large group of different mutants which 
among their somatic characteristics also have divergent wings. 
To my great astonishment Dr. WINGE now states in his paper 
that he received the original individuals on which his investigation 
is based “under the designation “spread” (wings) (p. 323), and 
through his whole work he believes to have investigated this III 
chromosome recessive, while as a matter of fact he has been 
working with the ordinar dominant mutant Dichaete from a stock 
in which the presence of another closely linked lethal was well 
known. 
The only way of explaining this regrettable misidentification is. 
*) A. H. Sturtevant 1918. An analysis of the effect os selection. Carne- 
gie Publ. of Wash. No. 264. ; 
| *) I also later handed the stock over to Dr. BONNIER, Stockholm, who inten- 
ded to locate the lethal mentioned. 
