56 ANIMALCULA OF INFUSIONS, L 



trated in the middle, that very few were frozen 

 in the reft of the infufion. 



What I have hitherto related proves that thefc 

 fpecies of animalcula do not periih at 13° under 

 freezing : but do they perifh becaufe cold has 

 deftroyed them, or becaufe the infufions have 

 loft their fluidity, for I have uniformly found, 

 when infufions dried up, the animalcula were ir- 

 recoverably dead ? The matter was dubious, 

 nor could it be elucidated unlefs by farther expe- 

 riment. It was neceffary to augment the cold 

 below 19°, and at the fame time prevent the 

 fluid from freezing. Both the one and the other 

 were eafily accomplifl^.ed, by means of artificial 

 cold, or a mixture- of fait, fnow, and common 

 water, in which animalcula that had died at: 

 vg^ were put. It is well known to philcfophers, 

 that water does not lofe its fluidity at 20°, nay, 

 at 21° below freezing, if at perfeft reft, which 

 is attained by inclufion in a veffel, and re- 

 moval from all external motion. Thus I dif- 

 covered that 19° had not been fatal to the ani- 

 malcula but the freezing of the infufions, fmce 

 at 12° ail were alive and fwimmJng about, though 

 with much lefs" velocity than ufual. Some fpe- 

 cies could fupport no more, for they died, at 12^, 

 though the water was not frozen, but began to 

 be covered with a thin film. Two fpecies ftill 

 furvived, and perhaps, or even without perhaps, 



mighs 



