BIOLOGISTS' WORK FOR THE INDUSTRY 227 



tance than that of tho effect of varying natural conditions on 

 their growth. What conditions are best, is the question that 

 needs answering. We hâve foiind that hght is very detrimental 

 to the mussel, full sunhght stunting it to less than one-third of 

 the size attained in the dark. Mr. H. S. Coulthard has been 

 studying the effects of varying amounts of Ught, of varying 

 positions in the tidal zone, and of varions températures on the 

 growth of the mussel, and the results obtained will be in part 

 appUcable to other more valuable shellfish. 



Prof. A. D. Robertson, of London, has been investigating 

 the growth of the oyster under various natural conditions, as 

 they occur in Richmond bay and in the Hillsborough estuary, 

 P. E. I. His results foiTn a basis for the rational planting of 

 oysters. 



Rearing Experiments 



That the fisheries are being depleted and that the waters 

 should be restocked in some way is a never ceasing cry. Unfor- 

 tunately we still bave ail too little knowledge as to what are 

 proper conditions for successful natural or artificial restocking, 

 and also as to where such conditions are to be found. We hâve 

 discovered an enormous contrast between the Magdalen shal- 

 lows (southern part of the Gulf of St. Lawrence) and the Bay 

 of Fundy as breeding places for many fishes and other forms 

 of life. Why should the breeding of cod, mackerel, lobster, oys- 

 ter, etc., be such a failure in the Bay of Fundy ? In this connec- 

 tion we hâve just fiuished artificially rearing lobster fry under 

 various conditions in the laboratory. The rearing of thèse fry 

 is a method extensively used in some places for restocking waters. 

 We hâve found that lobster fry are killed by several days expo- 

 sure to full sunlight when ail other conditions are kept right. 

 We hâve reared them successfully in the shade or in the dark 

 at various températures, namely 77 deg., 68 deg., and 59 deg. 

 F. from the time of hatching up to and even beyond the fourth 

 stage, but at 50 deg. they ail died before or when going into 

 the second stagCj while at 41 deg. they did not develop at ail. 



