PROGRESS IN BIOLOGICAL INQUIRIES, 1938 65 
the trout present and on stream conditions in general. While streams 
in the Pisgah Forest received most attention, a start was made in 
studying the main streams of the Cherokee, Chattahoochee, and Nan- 
tahala National Forests, where food conditions appear to be much 
the same as in streams of the Pisgah Forest. 
In general, the forest streams in this region may be classified as 
medium to poor. Most of them still suffer from excess of sediment, 
due largely to road construction and in some parts of the Pisgah 
Forest to overbrowsing by deer. However, conditions appear to be 
improving and were it not for uncertainties in future road construc- 
tion the outlook would be distinctly encouraging. 
Feeding experiments Extensive feeding experiments with finger- 
ling, yearling, and adult trout were carried on at the Leetown station, 
supplemented by experiments with fingerlings at the Pittsford sta- 
tion. These experiments were designed primarily to determine the 
effect on growth, mortality, and egg production of dry meals fed at 
different levels and in different combinations. 
In general, it was found that fresh meat is more efficiently con- 
verted into fish flesh than dry feeds but, owing to the lower cost of 
the latter, it 1s more economical to incorporate a considerable per- 
centage of these products into the diet. Using a mixture of the better 
dry meals, best resuits were obtained when the meals were fed at a 
level of 40-50 percent. 
One of the most striking results was the marked increase in growth 
following the addition of 3 percent cod-liver oil to a diet composed of 
sheep-liver and whitefish meal. Overfeeding failed to produce high 
mortality or any evident pathological effects. 
Experiments with brood fish showed considerable variation in the 
hatchability of eggs from fish on different diets, amounting in some 
cases to over 50 percent. Overfed lots produced twice the number of 
eggs per female obtained from underfed fish on the same diet but the 
percentage of eyed eggs was more than 10 percent greater in the 
underfed lot. 
Cooperative nutrition studies—Studies on the nutrition of trout 
were continued under the cooperative agreement between the Bureau 
of Fisheries, the New York Conservation Department, and Cornell 
University. These investigations are carried out at the Laboratory of 
Animal Nutrition of the New York State College of Agriculture at 
Ithaca, N. Y., and at the Cortland (N. Y.) Hatchery of the Bureau 
of Fisheries. The staff conducting these studies consists of Dr. C. M. 
McCay, A. V. Tunison, A. M. Phillips, E. O. Rodgers, and C. R. 
Mitchell. Inasmuch as detailed reports of the progress of these in- 
vestigations are published annually by the New York Conservation 
Department, only a summary of the results is included in this report. 
The study of the growth rates of four species of trout during a 
period of more than 5 years (March 10, 1933-September 16, 1938) has 
been terminated. The trout used were lake, brown, rainbow, and 
brook. In this study the best survivors were the lake trout. These 
continued to grow, but at a very slow rate, until discarded. The 
brook trout were the poorest from the point of view of survival. 
The growth curves of these four species ran parallel throughout. 
During the past few years many new vitamin concentrates have 
been made available, opening new possibilities for determining the 
needs of animals for vitamins. During the past year new studies 
