778 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [16] 



Eecapitulating, we have learned that it is easy to keep the water in 

 the incubators pure and sweet. We found that it was not safe to alter 

 the specific gravity of the water which was normal to the eggs and 

 spermatozoa. We learned, too, that with the highest temperatures we 

 did not get the best results. Our experience with the fixation of the 

 fry was very unsatisfactory, but we have observed enough to lead us to 

 the conclusion that the fixation may occur very early or within twenty 

 hours of the time of fertilization. We have found that we were pre- 

 viously in the habit of using too much milt ; that this tended to establish 

 putrescent action in the water in which the embryos were developing. 

 The air-blast did not prevent the putrescent action alluded to when too 

 much milt was used ; in fact we abandoned it after discovering that we 

 got just as good results without its use. Every adverse condition which 

 we could think of was met by us with some proviso in the arrangement 

 •of our apparatus, yet we cannot claim a full measure of success. We 

 have materially improved the extraction of the eggs and milt from the 

 adults, and made the methods of fertilization more simple and effective 

 by using less milt. After dealing with many millions of ova, under a 

 great variety of conditions, it is natural that we should have made some 

 progress, as indicated by the foregoing recital of our experieuces. The 

 effect of free caustic lime added in solution to the water in the incubators 

 was not clearly of any advantage, nor was the presence of oyster-shells of 

 apparently any more importance, as was shown by our final experiments. 

 The amount of carbonate of lime in the water necessary to the oyster is 

 necessarily very minute. On the chalky coast of the English Channel 

 lime is found only in the proportion of .0057 parts to 100 of water, and 

 the Rhine at Bonn, it has been estimated by Bischof, would supply 

 lime enough to form a mass of oysters covering four square miles to a 

 <lepth of a foot. It must also be borne in mind that the great tribu- 

 taries of the Chesapeake are constantly carrying vast supplies of lime 

 into the bay in an imperceptible form. That artificial supplies of lime 

 will determine the more rapid development of the shell of the embryo 

 oyster appears to me not yet very clearly demonstrated. The difficulties 

 in our way are probably not as great as we suppose, and the simple and 

 practical manner in which some one will one day solve the question 

 may verv probably surprise all of us. 



[Since the foregoing was written M. Brandely has published the results 

 of his work upon the Portuguese oyster, upon which he was engaged at 

 the very time we were conducting the experiments above described. 

 An even simpler method than that devised by M. Brandely was found 

 to give very promising results at the hands of the writer at Stockton, 

 Md., on the premises of Messrs. Shepard and Pierce; and by that method, 

 devised and put into prgictice within the next twelve months, a very im- 

 portant advance was made in the practical culture of the American oys- 

 ter, as already very fully described in a paper, by the author, cited in the 

 first part of this article.] 



