754 EEPOKT OF COMMISSIONER OF FISH AND FISHERIES. [14] 



advanced stage, and generally at Beaufort we noticed that tbougli the 

 development did not proceed much, if any, beyond the stages described 

 and figured by Brooks three years before, yet the rate of develop- 

 ment was very much increased, the embryo arriving at the most ad- 

 vanced stage in forty-eight hours, while in 1879 it had required some 

 seven and eight days to reach the same point. Dr. Brooks informs me 

 that his earliest experiments, those prior to my arrival, were the most 

 successful, and that he succeeded in maintaining the embryo alive until 

 they had advanced considerably beyond any stage described by him. 

 The experiments subsequent to my arrival were not so successful, ex- 

 cept in the respect noted, viz, the increased rate of development, and 

 this appeared to be due to the addition of the lime to the water. A 

 few experiments in which lime was not used gave rather conflicting re- 

 sults, the embryos reaching the advanced stages in nearly the same time, 

 but in much smaller numbers. I should say that fully one hundred 

 lived in the water containing the shells to one that survived in the 

 other. 



The rapid advance was so gratifying, and the addition of lime, which 

 was the only essential change from the previous methods of experiment- 

 ing, seemed so conclusively its cause, that both Dr. Brooks and myself 

 have been, perhaps, too sanguine of success from the use of the shells 

 and, perhaps, too hasty in assigning to them so much influence. At 

 Fair Haven I was unable to obtain nearly so good results though I used 

 besides the shells quantities of precipitated chalk which should have 

 been more easily decomposed than the shells. I found the embryonic 

 shells in this latter case to require from four to six days to develop, which 

 is not a very material advance over Brooks's results in 1879. Viewing 

 that fact together with the results of the experiments at Beaufort, es- 

 pecially those conducted without the assistance of the lime, I am of the 

 opinion that the influence of that factor is not so great by any means as 

 I had supposed, and that the success we met with in the early part of 

 the season must be assigned to other causes, though the supply of lime 

 may have rendered, and probably did render, some assistance. 



Presence of Infusoria. — A short time after placing the swimming em- 

 bryos in new water, even though all care is used and all precautions 

 observed, infusoria will begin to appear and thenceforward will exer- 

 cise a more or less deleterious influence upon the success of the experi- 

 ment. It is impossible to obviate this difficulty though care in select- 

 ing the oyster and in manipulating the eggs may do much to diminish 

 the evil. Attention should also be given to the water selected, which, 

 so far as my experience goes, should be recently taken from the sea. If 

 shells are used in the jars or plates, they should be thoroughly cleaned 

 and boiled before using them. But notwithstanding all precautions 

 which may be taken, the entire absence of infusoria cannot be secured. 

 Numbers of embryos will die and decompose, and the infusoria result- 

 ing will constantly increase. 



