REPORT OF COMMISSIONERS OF INLAND FISHERIES. 43 



source of the food of marine fishes is the microscopic life of the sea, 

 and therefore a thorough knowledge of the marine plankton, both from 

 a qualitative and quantitive point of view, and the factors which in- 

 fluence its abundance and distribution, would unquestionably afford 

 a basis for substantial progress in our knowledge of the life history of 

 the fishes. Much has already been done in this line, but so far as it 

 concerns our marine fishes, our effective knowledge of the plankton is 

 but in* its infancy. 



Another investigation which would be very fruitful of results in 

 comparison with the time and energy necessaiy for its prosecution, 

 is a thorough study of the eggs and young of the fishes. Various 

 European fishery organizations (Board of Fisheries of Scotland, 

 Marine Biological Association of the United Kingdom, Conseil per- 

 manent international pour Texploration de la mer; Commission zur 

 wissenschaftlichen Untersuchung der deutschen Meere) have carried 

 on this sort of investigation very successfully, but owing to the com- 

 parative neglect of this important subject by American investigators, 

 a large amount of work still remains to be done in the description 

 and identification of the eggs and larvae of different species of our 

 marine fishes. Such work is a necessary preliminary to a study of the 

 distribution and abundance of the eggs and larvae of fishes, and of the 

 physical and biological conditions influencing them. The eggs of 

 many of the more common species have been seen by various observers 

 and certain isolated statements regarding them exist in the literature. 

 Few of these eggs, however, have been figured and fewer still have 

 been studied with any completeness with reference to the identifica- 

 tion of the eggs of different species during the successive stages of 

 development. Similar statements might be made regarding our 

 knowledge of the larval and young stages of the fishes. 



The greatest contribution to such knowledge as we possess of the 

 early stages of our fishes has been made by various European workers. 

 Our knowledge is fairly complete regarding those forms like the 

 herring, mackerel, cod, etc., which are common to both shores. 

 Of American investigators of this subject, J. A. Ryder has made the 



