•■If4 ANIMALCULA OF INFUSIONS* U 



die external air to the veflels, or, being mixed 

 with the infufions, it concurs to aid the expan- 

 iion of them. That fuch germs may be partly 

 mixed with infufions, and the air promote their 

 ■evolution, I have no difficulty in believing. 

 But the fads hitherto related, evidently demon- 

 lirate that the air ferves as a vehicle to them ; and 

 as it is impoffible in this cafe to recur to thofe of 

 the infufion, which fliould have been deftroyed by 

 boiling for an hour, we are under the neceffity of 

 referring to thofe of the air. This fluid entering 

 more freely and copioully, fhould convey a much 

 greater number of ge nis into the open velTels, 

 and of confequence the population of the infu- 

 fions fhould be greater. The reverfe will hap- 

 pen, where little air enters and penetrates with 

 more difficulty, as when the veflels are fl:opped 

 . with wood. The volume of air included in the 

 veflTels hermetically fealed, will produce the zni- 

 malcula appearing there, but fev/ in comparifon 

 to thofe in open veflTels, on account of the rare- 

 nefs of the producing germs, which are propor- 

 tioned to the fmall quantity of air that is never 

 renewed. 



CHAP. 



