PROGRESS IN BIOLOGICAL INQUIRIES, 1921. D1 
awarded a prize by the American Fisheries Society as the most 
important contribution in the application of biological science to the 
advancement of fish culture. A series of practic al < experiments based 
upon these results was conducted during the winter at one of the 
fish-cultural stations of the Bureau. Just before the close of the 
year they were transferred to another station where more ‘adequate 
facilities were available, and it is planned to continue them during 
the coming fiscal year that definite results may be obtained. 
PIINNOWS IN RELATION: TO FISH CULTURE. 
The smaller members of the minnow family are important to fish 
culture since they represent a primary source of food for more than 
20 of the larger food and game fishes. The success of the introduc- 
tion of game fish into streams or ponds necessarily depends to no 
small extent upon the suitability of the stream or pond for the sup- 
port of minnows. Hence the budget of knowledge requisite for 
efficient fish culture includes information reearding the food and 
other requirements of minnows. Therefore, while the study of min- 
nows by C. M. Breder and D. R. Crawford, scientific assistants, was 
conducted almost entirely outside of office hours and represents a by- 
product as it were, the results gained are of practical value. 
They studied six common species in the vicinity of the District of 
Columbia ; chub minnow, Semotilus bullaris,; red-bellied dace, Leucis- 
cus vandorsalis; Notropis procne; shiner or red fin, Votropis cor- 
nutus, black-nosed dace, Rhinichthys atronasus; cutlip, roglossum 
maxillingua. All were found to be predominantly carnivorous, in- 
sects forming the bull of the food taken, although two species, 
Notropis procne and Exoglossum marillingua, consumed much vege- 
table matter. Various worms, filamentous ales, and diatoms entered 
into the food in considerable quantities. These minnows are, there- 
fore, in direct competition with the young of important game fish 
and may even prey upon the fry of them. ‘Tt is suggested, therefore, 
that if minnows are introduced into ponds as food for game fish, 
discretion should be exercised regarding the use of larger ‘and more 
rapidly growing minnows, such as the ¢ hub minnow and red fin, which 
may outstrip young trout in growth and under some circumstances 
become a menace rather than a benefit. 
In all cases the suitability of the introduction depends both upon 
the species of minnow and upon the species of fish which is to be 
fostered, as, well as upon other conditions prevailing in the water and 
upon the degree to which the various factors are under the control 
of the fish culturist.. Minnows seem to thrive best in streams or 
ponds where the banks bear overhanging vegetation that supports 
an abundance of insect life. Where this condition prevails there is 
probably less likelihood that the minnows will prey upon the eggs 
or young of other fishes. 
A NEW FORM OF POND OUTLET. 
Practical success in fish culture depends in no little measure upon 
economy in construction and operation of the pond and upon the 
convenience with which it can be drained for removal of brood stock 
or young, elimination of enemies, cleaning the bottom, or removing 
obnoxious plants. The concrete-box outlets commonly used are not 
