486 PHILOSOPHICAL TRANSACTIONS. [aNNO I67O. 



might give me a sufficient inducement to make the following experiment, that 

 several sorts of animals would be presently killed in our vacuum by withdrawing 

 the air, and even the insects mentioned in the formerly published digression 

 about respiration, though they also were not totally deprived of life'by the ab- 

 sence of the air, yet were of visible motion : Wherefore some good hint or 

 other being to be hoped for from the discovering, whether or no a separated 

 heart, which is but a part of an animal, would continue its motions in our 

 vacuum ; we made some trials to that purpose, whose success I find thus set 

 down : 



Exp. I. — The heart of an eel being taken out, and laid upon a plate of tin in 

 a small receiver, we perceived it beat there as it had done in the open air; we 

 then exhausted the vessel, and saw, that, though the heart grew very tumid, 

 and here and there sent forth little bubbles, yet it continued to beat as mani- 

 festly as before, and seemed to do so more swiftly. The heart of another eel, 

 being likewise taken out, continued to beat in the emptied receiver, as the 

 former had done. 



Exp. II. — ^The heart of another eel, after having been included in a receiver 

 first exhausted, and then accurately secured from leaking, though it appeared 

 very tumid, continued to beat there an hour; after which looking upon it, and 

 finding its motion very languid, and almost ceased, by breathing a little upon 

 that part of the glass where the heart was, it quickly regained motion, which I 

 observed a while; and an hour after, finding it to seem almost quite gone, I was 

 able to renew it by the application of a little more warmth. At the end of the 

 third hour, coming to look at it once more, a bubble, that appeared to be 

 placed between the auricle and the heart, seemed to have now and then a little 

 trembling motion ; but I found it so faint, that I could no more by warmth 

 excite it so as plainly to perceive the heart to move : wherefore I suffered the 

 outward air to rush in, but could not discern that thereby the heart regained 

 any sensible motion, though assisted with the warmth of my breath and hands. 



The Tenth Title. 



A Comparison of the Times wherein Animals may he killed by Drowning , or with- 

 drawing of the Air, 



To help myself and others to judge the better of some difficulties concerning 

 respiration, I thought it might be useful, that we compared together the times, 

 wherein animals may be killed by that want of respiration which in those that 

 are drowned is caused by the water that suffocates them, and that other want 

 which proceeds from withdrawing the ambient air. Of the latter of these a 



