PROPOSED IMPROVED METHOD OF CULTURE 119 



blindly followed. They are of advantage, but they lack intelligent ad- 

 justment to the locality and the season. Since temperature plays so im- 

 portant a part in the growth and reproduction of oysters, and since the 

 temperature varies with localities and seasons, is is impossible to fix on a 

 date that is equally good for all places and all years. To be quite correct 

 the date should be decided for each locality and for every year. An ex- 

 pert, instructed and qualified in the method of taking plankton and in 

 identifying and following up the progress of the oyster larva?, can tell 

 almost to a day when, for any situation and for any season, is going to be 

 or is the best time to put out cultch so as to secure the greatest set of 

 spat. A general yearly date, such as the last week of June or the first 

 week of July, may be sufficiently close to meet with some success or be 

 useful as a time for which to have preparations made, but the best results 

 can only be reached by taking into account all the accessible information 

 relative to the special occasion, and combining the two most important 

 factors of the maximum number of full-grown larvae on the one hand 

 and an abundance of good fresh cultch on the other. It might even be 

 advisable, under some circumstances, to divide and distribute the cultch 

 in such a way as to accommodate different broods of larvse, or to meet 

 weather conditions. 



This method does not start with eggs, like the artificial and restricted 

 experimental method of the few zoologists who can raise up young oysters 

 to the early conchiferous stage of the larva, but, from the inability to supply 

 suitable food, aeration and temperature, are incapable of carrying them 

 beyond that point. Some day it may be possible to cultivate diatoms 

 side by side with the oyster larvae they are to nourish, and then perhaps 

 the larvae may be artificially grown to the spatting stage. Neither does 

 the method start with spat oysters of considerable size, purchased as seed 

 or collected at favourable points, like the historic method of oyster culture 

 in England, France, Holland, the United States and other countries. It 

 takes account of both methods and begins between them, just in time to 

 avoid the mishaps of the former and to strengthen the one weak point 

 in the latter, viz., the difficulty of procuring spat. It allows the de- 

 veloping young to pursue their natural course as long as there is no over- 

 whelmingly destructive condition to be met. It takes advantage of the 

 colossal number of larvae lavishly provided by nature to offset the ex- 

 igencies and accidents of life and ensure a reasonable chance of keeping 

 up the stock. It places in their way the conditions best fitted for their 

 requirements. I believe that all the artificially fertilized eggs that could 

 be turned out into the sea would not materially alter the number of suc- 

 cessful spat. Of the countless millions of oyster larvae in the water about 

 oyster beds, but relatively few find suitable natural places for fixation. 

 Numerical comparisons of the umbo-stages of oyster larvae in the plankton 

 and of the young spat that follow in the same regions prove that this is 



