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which fwells up into bubbles by the 

 heat of the fun ; and that the cold 

 of the night is the reafon why thefe 

 air bubbles do not make their ap- 

 pearance at that time. As he found 

 that dry leaves put under water ga- 

 ther fuch bubbles alio upon their 

 furface, he concludes, p. 33, that 

 the appearance of thefe bubbles can- 

 not be owing to any vital action in 

 the leaves. 



I took fome pains to difcl'^fe the 

 caufe of thefe bubbles, which, I 

 think, are of more importance than 

 Mr. Bonnet at that time imagined 

 them to be; and found the fact, to 

 be generally this: . 



The mofl part of leaves gather 

 thefe bubbles upon their furface, 

 when plunged in any water in the 

 fun-mine or by day-time in the 

 open air; but infinitely more in 

 B z freih 



