120 COMMISSION OF CONSERVATION 



at least one point in the life-history of the oyster at which the greatest 

 destruction takes place. This is also one point at which it is in the power 

 of man to render assistance. The suggested manner of doing it is not 

 new, but the method of determining the exact time to do it, is new, and 

 that is the all important thing. Hitherto we have had no reliable method 

 of calculating the right time. The time of spawning, even if it were prac- 

 ticable for it to be carefully judged by extensive and accurate examination 

 by a competent zoologist, is too remote from the critical point of spat- 

 ting to be of great service. The observation of spat already deposited 

 comes too late for application. The taking and examining of plankton 

 is the only practicable and reliable method of becoming informed as to 

 whether it is worth while putting out cultch at all and, if so, at what time 

 it should be done. For the two seasons with which I am acquainted at 

 Malpeque the proper time did not arrive until nearly the middle of August. 

 It may require considerable patience and assurance to quietly hold cultch 

 until this time of the year, but it is exactly this assurance which the facts 

 of observation substantiate. The facts are so plain and reasonable as 

 to almost remove the process of spat-catching from the region of doubt, 

 caprice and chance, to that of expectancy, regularity and certainty. It 

 makes oyster culture as sure as farming. 



It may be that in the United States the time for planting cultch is 

 earlier than in Canada; that in more southern latitudes there is not such 

 a definite approach to a periodicity in spawning, swarming and spatting; 

 that in some places an oyster can develop and deposit spawn a second 

 time in the same season. These and other questions need re-examining. The 

 prevalent, mistaken belief in a very short larval period, and the practice 

 of gauging cultch-planting by the doubtfully determined time of spawning, 

 a month before spatting takes place, can not but have led to many kinds 

 of errors. When all such subjects are again examined by capable men, 

 with improved methods, I feel sure that both theory and practice will be 

 put on a much surer footing. 



The researches of Brooks and his co-workers put American away 

 ahead of European knowledge of the oyster, but still left unknown the 

 natural life of the larva. The larval life of the oyster and of its associates 

 among bivalve molluscs was the last obscure chapter in the general history 

 of development of these animals and in the data for a comparative embry- 

 ology. This was due to the lack of application of plankton methods in 

 the study of the larval periods of marine animals. The systematic employ- 

 ment of plankton methods in the discovery of bivalve larvae in their 

 natural habitat, combined with parallel faunistic studies of the same 

 regions, have now made it possible to clear up this obscurity in the 

 life-history of the oyster, and to apply the knowledge gained as an 

 important addition to the practical methods in use for oyster culture. 



