PKOGEESS IX BIOLOGICAL INQUIRIES 63 



of pure foods with varying vitamin constituents has been deter- 

 mined and chemical analyses have been made on such animals after 

 they had been fed for a year. 



Studies have also been made on the amount of food consumed by 

 fishes of various ages at different temperatures. In this connection 

 the metabolic rat*, as indicated by oxygen consumption, has been 

 determined. It has been found that fishes soon become acclimatized 

 when they are placed in water of a different temperature from that 

 in which they were previously kept and there are characteristic 

 differences in their metabolic processes. The chemical changes in 

 the blood of fishes that are starved, fed, or subjected to other condi- 

 tions are being investigated. 



BIOLOGICAL LABORATORIES 



The Woods Hole (Mass.) biological laboratoiy was open as usual 

 during the summer of 1924, with Dr. W. H. Rich acting as director. 

 Twenty-two independent investigators availed themselves of the 

 facilities afforded and conducted several valuable researches. 



Dr. Edwin Linton and Dr. G. A. MacCallum continued their in- 

 vestigations on the parasites of fishes. Dr. F. G. Hall, of Miltoti 

 College, and Dr. S. LepkoAvslry' undertook a study of the blood of 

 fishes, which promises important results. It was found that the 

 oxygen-carrying capacity of the blood in different fishes is corre- 

 lated in general with the activity of that particular species. There 

 is also a correlation with the rate of metabolism of the fish Avhen at 

 rest. Perhaps the most significant results were in respect to changes 

 that take place in the blood volume. A study was made of the ex- 

 ternal conditions that have an influence on the blood volume, and it 

 was found that changes in salinity and oxygen tensions apparently 

 were the most important of these. 



Dr. N. A. Cobb, of the Department of Agriculture, continued an 

 important investigation on the marine nematode fauna of the Woods 

 Hole region. Many additional species were discovered, most of 

 which are new to science. Attention is being given to the ecological 

 relations which may exist between nematodes and fishes. 



Paul S. Conger, of the Carnegie Institution of Washington, con- 

 tinued his research on diatoms, which has been carried on for a num- 

 ber of years under the direction of Dr. Albert Mann, also of the 

 Carnegie institution. Approximately 100 samples were taken, about 

 80 of which were dredged and the rest secured by means of tow nets.. 

 This work is intended to provide material and data for a study of 

 the seasonal distribution of the diatoms and to serve as a basis for 

 a manual of the diatom flora of the Woods Hole region. Attention 

 is also being given to a study of the stomach contents of bottom- 

 dwelling animals in order to get more definite ideas of the impor- 

 tance of diatoms in the food cycle of the sea. 



Mary G. Springer conducted an investigation on the nervous 

 mechanism of respiration in the dogfish, and some significant and 

 important conclusions were reached. 



In addition to the activities of the independent investigators, the 

 laboratory was used by Dr. P. S. Galtsoff, Dr. C. J. Fish, and Marie 

 D. P. Fish, regular employees of the bureau. The results of the 



