I, ANIMALCULA OF INFUSIONS. ^9 



the influence of heat, but at length yield under 

 it. As the higher clafs does not originate unlefs 

 at a much more moderate degree of heat, there 

 is a neceflary inference, that the germs of this 

 clafs are much fooner affected than thofe of the 

 lower ; whence we mud conclude, that the amaz- 

 ing multitude of animalcula in the infufions of 

 open veffels expofed to boiling heat, and the in- 

 tenfe flame of the blow pipe, do not appear be- 

 caufe their germs have r uiiitd fo great a degree 

 of heat, but becaufe other germs have come to 

 the infufions after cefTation of the heat. 



But is there any proof, or any forcible argu- 

 ment, CO remove or leifen our natural repugnance 

 to fuppofe that germs of the lower animalcula 

 can refill: the heat of boiling water ? To fpeak 

 pfth^ germs or eggs of animals known to us, are 

 there none of this nature ? Undoubtedly, as far 

 as our knowledge extends, we are unacquainted 

 with any of that defcription. Something has 

 been faid on the fubjeQ: in the ninth chapter of my 

 DiiTertation, demonftrating how the eggs of va^ 

 rious infe£ls, as well as thofe of birds, perilh at a 

 degree of heat confiderably lefs than that of boil- 

 ing water. It is further fhown, that this heat in- 

 jures the feeds of plants, even thofe with the 

 hardeft fhell. A greater number of feeds and eggs, 

 indeed, might have been fubjeded to experiment : 

 and fome may be found capable of Handing the 



tri^L 



