72 
to March. Correspondingly, without cyclones, 
the summers are practically rainless. 
The diverse rainfall types of the United 
States as well as the essential features of the 
distribution of rainfall may be held in mind 
if the essential faetures which produce rain- 
fall are remembered. 
Cuartes F. Brooxs 
CoLLEGE STATION, TEXAS 
SPECIAL ARTICLES 
A PARALLEL MUTATION IN DROSOPHILA 
FUNEBRIS 
A muTANT of Drosophila funebris Fabr. has 
recently appeared that is so strikingly similar 
to a well-known mutant of D. melanogaster . 
Meig. (ampelophila Loew) that there can be 
litle doubt that the same mutation has oc- 
curred independently in the two species. The 
new form, called notch, agrees with the notch 
melanogaster in at least eight different re- 
spects, as will appear below. 
Origin.—A female funebris of a stock from 
Mitchell, S. D., was mated to a male of a 
stock from New York City. The descendants 
were mated in pairs for several generations, 
and no variations were observed except an 0c- 
easional fly with one of the anterior scutellar 
bristles missing. Such flies were found also 
in the uncrossed New York stock. In the line 
under consideration selection was carried on, 
in an attempt to increase the percentage of 
such flies, but no marked result was obtained. 
In F, one pair (5201) produced 35 normal 
females, 34 notch females, and 36 normal 
males. The sex ratio here is significant, since 
an excess of males is more frequent than an ex- 
cess of females in this species. The pair from 
which the parents of 5201 came produced 19 
females and 31 males, which is not an unusual 
excess when complete counts are not obtained. 
In D. funebris the males usually emerge in a 
little less time than the females. This re- 
lation is just the reverse of that found in 
D. melanogaster. Evidently the female parent 
of 5201 was genetically notch. She was not 
observed to be abnormal, and had been de- 
stroyed when her offspring began to emerge. 
It seems probable that she did not have 
SCIENCE 
[N. S. Vou. XLVIII. No. 1229 
notched wings, but she may well have had the 
characteristic veins and acrostichal hairs, since 
these would more easily have been overlooked. 
Description—Notch melanogaster is char- 
acterized by having the wings somewhat 
nicked, more especially at the apical posterior 
corner. But this character is somewhat va- 
viable, being often unlike in the two wings of 
the same female, and sometimes even entirely 
absent.2 
In addition the eyes are often smaller than 
those of the wild-type flies and somewhat 
roughened.? 
Furthermore the veins of notch are some- 
what thickened, more especially the apical por- 
tions of the second and fifth longitudinal 
veins. This character. is the most invariable 
and convenient index of the presence of the 
notch gene. The anterior scutellar bristles of 
notch are often doubled. The acrostichal hairs 
are more numerous than those of the wild- 
type fly, and are irregularly arranged, in- 
stead of being in eight fairly définite rows.® 
The notch gene thus produces an unusually 
large number of morphological peculiarities. 
Notch funebris agrees in all of the above 
respects. The wings are nicked in the same 
way, but are often asymimetrical and some- 
times normal; the eyes are often small and 
roughened; the wing veins are thickened even 
more than those of notch melanogaster, the 
second and fifth being affected most, and this 
character being again the most convenient 
and reliable for purposes of classification; the 
anterior scutellar bristles are often doubled, 
in spite of the fact that notch arose in a 
family selected for the absence of these bris- 
tles; the acrostichal hairs are irregularly ar- 
1 See Morgan, 1917, ‘‘The Theory of the Gene,’’ 
Amer. Nat., 51, for figure and a discussion of this 
variability. 
2 Bridges has shown that notch is probably an 
allelomorph of the roughened eye known as facet. 
Metz and Bridges, 1917, ‘‘Incompatibility of Mu- 
tant Races in Drosophila,’’ Proc. Nat. Acad. Sci., 3. 
3The peculiarity of the acrostichal hairs was 
not observed here until it was looked for after 
notch funebris was found to have unusual acro- 
stichals. 
