496 PHILOSOPHICAL TRANSACTIONS. [aNNO I67O. 



Therefore considering with myself what happens to infants and other young 

 animals in the womb, and even after they come from thence, if they continue 

 to be wrapt up in the secundines ; though as soon as they are brought into the 

 free air they may be presently killed by being kept from breathing : consider- 

 ing also what I elsewhere relate of the slow expiration of a very young kitling 

 in our vacuum ; together with the long want of respiration, which custom 

 enables some divers to endure : considering these things, I say, though I know 

 that somewhat may be objected to show that these instances are not altoge- 

 ther full to my purpose ; yet they, among other things, invited me to think 

 that the least unlikely projects that occurred to my barren invention, would be 

 these that follow. 



First, I thought fit to try, whether the seeds of respiring animals might be 

 either hatched or otherwise brought to produce young ones in our vacuum. 

 For, if that could be compassed, I should obtain my end. 



Next, in case of my failing in the former attempt, and that which is to be 

 after a few lines proposed, I thought fit to try, whether at least I could not 

 bring the eggs of insects to hatch or be animated ; or aurelias (as they call 

 them) that were already alive, turn according to the course of nature, into 

 winged insects, as flies or butter-fishes ; (of which trials and those of the 

 former sort, the account properly belongs to another place, where I relate the 

 success of these and other attempts to produce plants and animals in our 

 vacuum.) 



But thirdly, considering that nature has so ordered it, that frogs, though 

 when they are grown large enough to deserve that name, they be amphibious 

 animals endowed with lungs ; yet before they attain to it, live wholly in the 

 water like fishes ; I thought it the most expeditious and least improbable at- 

 tempt we could make, to try, whether or no this animal, being as a fish 

 brought to live either in our vacuum, or at least in highly rarefied air, would 

 not continue to do so, after its lungs should be perfectly formed. Wherefore, 

 though I foresaw and foretold the di^culty that would be met with in the pro- 

 secution of this experiment, namely, that the aerial bubbles that would be dis- 

 closed in such soft bodies upon the withdrawing of the pressure of the ambient, 

 would so violate the slight texture of those tender animals, as to hinder them 

 from living long or moving freely ; yet I thought it very fit to attempt the 

 trial. 



Exp. I. — ^We took a number of tadpoles, and put them with a convenient 

 quantity of water into a portable receiver of a round form, and observed, that 

 at the first exsuction of the air they rose to the top of the water, though most 

 of them subsided again, till the next exsuction raised them. The receiver 



