-460 MOHR, 6. WINGE’S PAPER “THE INTERACTION BETWEEN TWO 
the following: When I demonstrated the wing alteration of the 
Dichaete flies I may have called the mutant zz Norwegian “spredte 
vinger” which means that the wings are held out from the body. 
But I certainly never told that the culture mentioned was homozygous, 
and it never occurred to me to designate the Dichaete flies as “spread” 
of the simple reason that I never worked with this recessive, nor even 
ever had it among the cultures which I have brought over to Norway. 
At is surprising that Dr. Winge, who in his Fig. 1, p. 323, under the 
designation “typical spread” gives a correct picture of a Dichaete fly 
(bent wings, bristle alteration) is not aware of the fact thatthe peculiari-, 
ties exhibited by this fly are markedly different from those described 
as typical for the spread mutant. At any rate, I can only regret 
that Dr. WINGE, when he “to his great astonishment” discovered 
the — from his point of view — entirely unexpected genetic 
‘behaviour of the stock he had received, did not send me a word 
about it. A post card would have solved the problem which now 
„demanded the raising of 13.000 flies. 
When this mistake is cleared up, the results of Dr. WINGE 
need no further comment. They are all directly deducable from 
the known constitution of the stock which he obtained. Dr. WINGE 
gives no literature references, and one who is not familiar with 
the Drosophila literature might get the impression that this is the 
first investigation of a case like the one discussed above. It seems 
therefore advisable to recall the fact that numerous analogous cases 
of “balanced lethals” have previously been more fully worked out in 
Drosophila, among others especially by Dr. H. J. MULLER, who 
as well known, has used them for his important explanation of 
‘Oenothera “mutants”. In Dr. MORGANs last book (p. 257—266) a 
full account of analogous cases is given (MULLER’s Beaded case). 
Among them is also a case which is entirely indentical with the 
one here discussed, viz., a case described by Dr. STURTEVANT in- 
volving just the mutant Dichaete in combination with another lethal 
closely linked to this gene 1). 
') T. H. MORGAN 1919. The physical basis of heredity. Lippincot Co. Phila- 
‚delphia and London. 
BIT PO Ah LUE LOT OE ROE VB u SIR 

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