I. AITIMALCULA OF INFUSIONS. I99 



animalcula themfelves precipitated from the ex- 

 ternal air. Perhaps the communication of the 

 fubftances with the air may alfo facihtate their, dif- 

 •folution, and the generation of animalcula in con- 

 fequence. 



IV. By the clearefl: experiments, you have 

 happily refuted an important objection, that the al- 

 tered ftate of the air in the veffels had prejudiced 

 ■the vegetative power of fubftances infufed ; but 

 animalcula <:ontinued to appear in veiTels herme« 

 tically fealed expofed to boiling heat, fome from 

 half a minute to two minutes, others from fix mi- 

 nutes to twelve ( 1 ). The fmallefl animalcula 

 ionly originate, and none of the largefl: or middle 

 fized. Thus it feems fufficiently proved, that 

 thofe of the higher clafs cannot originate or ex- 

 pand in fubftances fubjeded to nmilar experi- 

 ments. A fa£t which may be -the fubjed of the 

 .mod profound mxcditation is demonftrated : the 

 Jmaller the animalcula are, the lefs injurious is 

 heat to their generation or developement. I fhall 

 foon return to this. If the higher clafles are 

 not feen in veffels hermetically fealed, and expof- 

 •ed • half a minute to boiling heat, cannot we 

 -thence conclude, that all the animalcula you have 

 .feen fo numerous in infufions boiled from .half an 

 N 4 . hour 



{ I ) Ebullition above twelve minutes has not obftruS.ed 

 tbe produdion of the fmallell animalcula. 



