PROGRESS IN BIOLOGICAL INQUIRIES, 1921. V7 
was that the top minnow, @ ambusia affinis, was very widely employed 
as an agent in the control of malaria. A report of observations made 
by Mr. “Hildebrand during this campaign has been published by the 
Public Health Service.® 
The latter part of the season was devoted to investigations at Sa- 
vannah, Ga., where a special effort was made to determine the relative 
value as eradic ators of mosquito larvee of two other American vivipa- 
rous species of fishes, /Zeterandria formosa and Mollienisia latipinna, 
both of which are abundant at Savannah. It was demonstrated that 
Heterandria formosa is of real value and is well worth careful con- 
sideration wherever it occurs. ollienisia latipinna, on the other 
hand, appeared to be practically worthless. 
The antimalaria campaigns in the various States were brought to 
a close early in November, in which month the annual meeting of the 
National Malaria Committee and the conference of. sanitary engi- 
neers engaged in antimalaria work took place in Louisville, Ky., 
where the outcome of the past season’s campaign was reported and 
discussed. ‘The subject of mosquito control by the use of top min- 
nows received extended discussion, and the fac t was brought out that 
nearly every sanitary engineer had made use of Gambusia affinis as 
an agent in malaria control with excellent results. The saving of 
large sums of money was reported, because fish control replaced other 
methods at much less expense. 
Similar advisory work was done by Mr. Hildebrand in the spring 
of 1921 before establishing headquarters at Augusta, Ga., for further 
investigations to determine more fully the conditions of effectiveness 
in the employment of fish for destruction of disease-bearing mos- 
quitoes. 
CONDITIONS GOVERNING ABUNDANCE OF MOSQUITO-DESTROYING FISH. 
R. L. Barney and Barry Anson have continued the organization 
and summarizing of data collected at Mound, La., where inv estiga- 
tions of the use ‘of fish for control of mosquito breeding were pre- 
viously conducted in cooperation with the Bureau of Entomology. 
Reports * printed outside the Bureau’s publications demonstrate 
the varying seasonal frequency of Gambusia, the mosquito-eating 
fish; the seasonal variation in the proportions of the sexes and its 
bearing on the abundance of the species in nature; the effect of en- 
vironment on the abundance of the species; and the relation of plants 
of varying habits of growth to oxygen supply and to the capacity of 
small ponds to support the top-minnow Gambusia. Further obser- 
vations have been made on the seasonal abundance of Gambusia, es- 
pecially in relation to the fecundity of the species. Appropriate con- 
sideration has been given certain points concerning the anatomy of 
the female reproductive organs of this fish. 
® Hildebrand, Samuel F.: Top Minnows in Relation to Malaria Control, With Notes on 
Their Habits and Distribution. Treasury Department, Public Health Bulletin No. 114, 
May, 1921, 34 p. Washington. 
* Barney, R, L., and Anson, B. J.: Relation of Certain Aquatic Plants to Oxygen Supply 
and to Capacity of Small Ponds to epyheie the Top-minnow (Gambusia affinis). Trans- 
actions, American Fisheries Society, 1920, 268-278. 
—. Abundance of the Mondnite Destroying Top-minnow Gambusia affinis, 
abe clalty in Relation to Male Frequency. Ecology, Vol. II, No. 1, January, 1921, pp. 
53-69. 
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