PROGRESS IN BIOLOGICAL INQUIRIES, 1924 37 



hydroids, by Dr. C. W. Hargitt; crabs, by Dr. Mary J. Rathbun; 

 macrura and anomura, by Dr. Waldo L. Schmitty amphipods, 

 cumacea, schizopods, pycnogonids, and isopods, by C. R. Shoemaker. 



Reports on the following are in progress, and it is hoped that they 

 will be completed during the fiscal year : Medusae, by Dr. Henry B. 

 Bigelow; Sagittae. by Prof. A. G. Huntsman; Bryozoa. by Dr. Ray- 

 mond C. Osborn; Algte. excepting diatoms, etc., by Dr. W. H. Hoyt; 

 MoUusca, by Dr. Paul Bartsch ; Nudibranchia. by F. N. Balch ; plank- 

 ton, by Dr. Bert Cunningham; Mysis. by Dr. R. P. Cowles and 

 M. Glassman; and fishes, by S. F. Hildebrand and W. C. Schroeder. 



The salinity determinations have been completed by Dr. R. C. 

 Wells, and these, together with determinations of densities by Dr. 

 R. P. Cowles, and observations on temperature, wind, tide, character 

 of bottom, and hydrogen-ion concentration, are being studied from 

 a comparative point of view with special reference to the biological 

 data. It is expected that Dr. Cowles will complete the report on this 

 phase of the work during the coming year. 



STUDIES OF MARINE PLANKTOX IX RELATION TO THE FISHERIES 



Young fish feed upon the minute forms of animals and plants, col- 

 lectively known as plankton, which are found everywhere but in 

 varying abundance in the sea water. Since the survival of the 

 young fish depends upon the presence of the proper plankton forms, 

 it is important to know just wdiicli of these forms the young fish 

 feed upon at various stages in their development. The larger adult 

 fish likewise depend eitjier directly or indirectly upon the plankton 

 for their nourishment. They may feed directly upon the larger 

 plankton forms, or their food may consist of other smaller fishes 

 that do feed directly on plankton. The importance of these small 

 marine forms in the economy of fish life is therefore obvious, and 

 no life history of the important food fishes can be complete without 

 taking into consideration the part played by the plankton. The in- 

 vestigation of plankton forms a connecting link between the life- 

 history studies of food fishes on the one hand and the study of phy- 

 sical and chemical oceanography on the other. Only through a 

 study of the plankton is it possible to know how, in general, chem- 

 ical and physical factors affect the abundance and distribution of 

 the food fishes. 



Dr. Charles J. Fish, attached to the Woods Hole laboratory 

 throughout the past year, continued his investigation of the daily 

 and seasonal variation in the plankton of the Woods Hole region. 

 The work, until July. 1923, had consisted of daily observations on 

 physical conditions and collections made from the end of the Bu- 

 reau of Fisheries* dock. During the summer the work was sup- 

 plemented by similar observations made throughout Vineyard Sound 

 and Buzzards Bay, the purpose being to determine the horizontal 

 distribution of the various planktonic organisms. Special collections 

 of larval fish were also made, to be used in a future investigation of 

 their feeding habits. 



Unusually cold weather prevailing throughout the spring of 1923 

 had a decided effect on the summer plankton of the region. Al- 

 most all of the pelagic forms appeared later than usual, and some 

 comparatively common animals did not appear at all. The diatom 



