1896.] NATURAL SCIENCES OF PHILADELPHIA. 277 



years steadily diminished in abundance, notwithstanding the enor- 

 mous quantity of plants spread out on the oyster grounds of our 

 seaboards, as well as that the fisheries of the Great Lakes have, in 

 several instances, grown steadily less profitable, notwithstanding 

 that millions of young fry have been liberated annually ; for unless 

 the transplanted organism can find suitable and abundant food, 

 the time and money spent in rearing it, up to the period of its plant- 

 ing, is practically wasted. 



As the result of the planktonic studies of Hensen, aquiculture is 

 taking on a new phase which promises to mark a period in its 

 history as important as has been seen in the very rapid development 

 of scientific agriculture, directly attributable to the teachings and 

 methods of Sir John Bennett Lawes of Rothamstead, England. 



A glance at recent literature is sufficient to show the marked con- 

 trast between modern planktonic investigation and the empirical 

 methods hitherto employed in aquiculture. 



Prof. H. B. Ward, in his paper on the " Food Supply of the Fish 

 in the Great Lakes," and Prof. J. E. Reighard, in his reports on the 

 "Biological Examination of Lake St. Clair," indicate very clearly that 

 the practical failure of fish culturists to replenish the rapidly dimin- 

 ishing supply of white fish in the Great Lakes may be directly at- 

 tributed to a lack of knowledge on the part of those conducting the 

 fish hatcheries, of the conditions aflfecting the primitive food supply 

 of these waters. In the work conducted under the direction of 

 Prof. Reighard, we find the first recognition in this country of the 

 prime importance of a knowledge of the protophytes of the plank- 

 ton, constituting as they do the primitive food supply upon which 

 are dependent all other forms of the plankton, as well as all higher 

 aquatic organisms. 



John P. Lotsy, in a study of the food of the oyster, clam and 

 ribbed mussel, confirms what has long been known, that these mol- 

 lusks feed almost entirely upon diatoms, and that a knowledge of 

 the life conditions of these latter must furnish the basis of intelligent 

 oyster culture. 



In reviewing the literature pertaining to oysters and the oyster 

 industries, frequent mention is found of the food of oysters and the 

 importance of an abundant and regular supply of the same, but no- 

 where in the numerous reports of expensive investigations of oyster 

 grounds, carried on by the various governments, do we find any sys- 

 tematic study of the protophytic plankton of the waters examined. 



