OP FISH IN GENERAL. 



Experiments by Mr. Hawkshec. 



subsist without air, Mr. Hawkshee made several 

 experiments, which are recorded in the philoso- 

 phical transactions. The fish he employed were 

 gudgeons: a species that are very lively in the 

 water, and can live a considerable time out of it. 

 Three of them were put into a glass vessel, with 

 about three pints of fresh water, which was de- 

 signed as a standard to compare the others by. 

 Into another glass, to a like quantity of water, 

 were put three more gudgeons, and thus the wa- 

 ter filled the glass to the very brim. Upon this 

 he screwed down a brass plate with a leather 

 below to prevent any communication between 

 the water and the external air, and, that it might 

 the better resemble a pond frozen over, he suf- 

 fered as little air as possible to remain on the 

 surface of the water. A third glass had the 

 same quantity of water put in it, which, first 

 by boiling, and then by continuing it a whole 

 night in vacuo, was purged of its air as well as 

 possible; and into this also were put three gud- 

 geons. In about half an hour, the fish in the 

 water from whence the air had been exhausted, 

 began to discover some signs of uneasiness, by a 

 more than ordinary motion in their mouths and 

 gills. Those that had no communication with 

 the external air, would at this time also fre- 

 quently ascend to the top, and suddenly swim 

 down again: and in this state they continued 

 for a considerable time, without any sensible al- 

 teration. About five hours after this observa- 

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