750 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [10] 



l)iit a very short exposure of the auimal to water of an increased tem- 

 peratnn^ caused a deterioration of the generative matter. 1 have tried 

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

 the Quinnipiac River and invariably failed ; the eggs in nearly every 

 case ai)peiired 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, gave 

 good results. 



b. The process of segmentation is liastened by a high temperature 

 and retarded by a k)\v. At Beaufort I experimented with several lots 

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

 All the eggs came from the same lot of oysters and wei"e fertilized at 

 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 fire, when the segmentation began and advanced 

 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 temi^erature or violent changes of tem- 

 perature destroys the egg. In the experiment mentioned above, though 

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

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

 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; but 

 I made no special study of this matter and cannot state with certainty 

 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 

 vsettlement 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 develoi)ment after 

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

 l)eratures tend to stop the progress of the egg. Without intending to 

 establish a fixed standard I am of the opinion that the teniperature 

 should be between 05° and 75° Fahrenheit, and that the nearer 70° it 

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

 I)erature 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 is 

 impossible to say. 



