O.WINGE’s PAPER ON“ THE INTERACTION BETWEEN 
TWO CLOSELY LINKED LETHALS IN DROSOPHILA 
AS THE CAUSE OF THE APPARENT CONSTANCY 
OF THE MUTANT “SPREAD””. 
A NECESSARY RECTIFICATION 
by Otto L. Mour 
(Anatomisk Institut, Christiania University, Norway) 
In Deel IV, Afl. 3 en 4 (Mei—Juli, 1922) of Genetica Dr. 0. WINGE, 
Copenhagen, publishes a paper with the above title. The main 
results of his investigation are contained in the following sum- 
mary (p. 337—338): 
1. “By examination of the mutant „Spread” (wings) of Drosophila 
melanogaster it appeared that Spread, located in the IlIrd 
‘chromosome at 61, is not — as stated in the literature — 
recessive but dominant (to normal wings). 
2. Spread acts lethally in double dose. 
3. The wild type possesses a dominant indispensable factor Vital 
(Vit) that is closely linked to spread. Its allelomorph, vit, 
also has a lethal effect in double dose. 
4, The formula of the spread mutant is a, thus it is double 
spr vit 
heterozygotic. It is only the strong linkage between Spr and 
Vit that causes that the Spread type seems to be constant. 
5. The distance between Spread and Vital is scarcely 1.0. 
6. The Spread mutant is an instance of a double heterozygote, 
which on account of two lethal factors (Spr and Vzt) reminds 
of and -has been construed as a constant homozygotic type.” 
These statements involve zater alia the following conclusions : 
a. The earlier Drosophila workers have made the mistake of 
