750 REPOKT OF COMMISSIONER OF FISH AND FISHERIES. [10 J 



bat a very short exposure of the animal to water of an increased tern 

 perature caused a deterioration of the generative matter. I have tried' 

 to fertilize the eggs of numbers of oysters that had lain over night ir 

 the Quinnipiac River and invariably failed ; the eggs in nearly ever;^; 

 case appeared to be over-ripe. Oysters taken from the bed at the same 

 time and from the same locality, but kept in a basket over night, gav( 

 good results. 



h. The process of segmentation is hastened by a high temperature^ 

 and retarded by a low. At Beaufort I experimented with several lot.^' 

 of oysters, or eggs rather, exposing them to different degrees of heat' 

 All the eggs came from the same lot of oysters and wer-e fertilized a1^ 

 the same time. They were exposed to a temperature ranging from 70^* 

 to 80°, and quite a marked difference was noted in the rate of segmen. 

 tation. At the same time a lot of eggs under Dr. Brooks's care made' 

 no advance in development for several hours (the night was a cool one; 

 until placed by the iire, when the segmentation began and advance(J 

 rapidly. I always noticed the retarding or destructive effects of loW 

 temperatures, both at Beaufort and Fair Haven. 



c. A very high or very low temperature or violent changes of tern" 

 perature destroys the ^gg. In the experiment mentioned above, thougrf 

 the eggs exposed to the high temperature (80o) advanced most rapidly, 

 yet but few reached the swimming stage. I noticed subsequently, a< 

 Fair Haven, the same circumstance. High temperature also appears' 

 to conduce to irregular segmentation, the egg dividing at once into 

 a number of segments, and the distinction between macromere and' 

 micromere not being so apparent as under ordinary circumstances 5 but' 

 I made no special study of this matter and cannot state with certaintj;' 

 that the irregularity is due to the high temperature. In 1879 Dr. Brooks 

 noted the destructive effects of low temperature, and though during 

 the past season I made no experiments having especially in view the^' 

 settlement of this point, yet as the invariable result of a few hours low' 

 temperature was the failure of the experiment in raising the egg, and,- 

 as there is but a very slight advance, if any, in the development after 

 the low temperature sets in, I think it safe to conclude that low tem' 

 peratures tend to stop the progress of the agg. Without intending to' 

 establish a fixed st^mdard I am of the opinion that the temperature 

 should be between 65° and 75° Fahrenheit, and that the nearer 70° it^ 

 is, the more likely is the experiment to be successful. Whatever tem- 

 perature is started with, the changes afterwards, during the segmen- 

 tation of the egg or development of the embryo, should be gradual. I 

 noticed that after a change of a few degrees, due to exposure to the'^ 

 rays of the sun, or to a cool shower of rain, or a squall of wind, my ex-; 

 periment usually failed. So far as it is possible to judge in the absence' 

 of experiments looking directly to the obtainment of information upon 

 this point, I consider a change to low temperature more disastrous than' 

 a change to high. How great a range can be safely permitted it \d 

 impossible to say. 



