25 



ed pain ; in a short time became less active ; but 

 symptoms of life were evident from four to six hours 

 in the different experiments which were performed. 



They live in nitrogen longer than we might sup- 

 pose, agreeably to its effects on other animals. When 

 we reflect on their living under ground, and the many 

 causes that may prevent them from coming to the 

 surface, we must be sensibly impressed with the wis- 

 dom of nature, in giving them constitutions suscepti- 

 ble of enduring a considerable space of time the pre- 

 scence of impure air. 



The worms that have been kept in this gas, remain 

 longer in a state of asphixia than when confined in any 

 other ; and may be recovered, by a proper mode of 

 treatment, after fifteen or twenty hours confinement. 



EXPERIMENT IV. 



I procured carbonic acid gas from pulverized mar- 

 ble, by the addition of the sulphuric acid, diluted with 

 water. I placed the extremity of the syphon so as to 

 receive the gas in the vessel in which the experiment 

 was to be performed. I caused a number of worms 

 to pass into the vessel containing the fixed air : imme- 

 diately after they came in contact with the air they 

 exhibited signs of pain, moved about rapidly, were 

 convulsed, and in ten minutes had the symptoms of 

 being dead. They were left in this situation precisely 

 one half hour; I then examined them, and found their 



D 



