L ANIMALCULA OF INFUSIONS.- 23 



a fingle one of the higher clafs in infufions her- 

 metically fealed, though they had fuifered only 

 the moderate heat of iii'^. 



This was done in the middle of July ; and the 

 thermometer in the fhade flood at 88°. Eighteen 

 Veflels were put to the teft : nine fuffered 99°, 

 and nine 88°. No animalcula of the higher 

 clafs were produced at 99° ; but the whole nine 

 infufions produced them at 88°. Animalcula- tht 

 fame in number and fpecies, were in each veffel, 

 as in the clofe infufions not fubjected to heat. 

 From this fad:, it was eafily difcovered, that the 

 degree of heat fatal to thefe animals was between 

 99° and 88° ; and I found it to be 95° : at 93°, 

 a few of the higher clafs appeared ; at 95°, only 

 thofe of the lower. 



The method of opening the infufions has been 

 defcribed towards the beginning of this chapter. 

 When clofe infufions were made, 1 alfo formed 

 open ones : and both being put in the fame 

 place, to have an equal temperature, when the 

 open infufions abounded with all forts of animal- 

 cula, 1 examined the clofe. Such a plan always 

 feemed the befl ; neverthelefs, if difappointed of 

 feeing animalcula, I changed it oftener than 

 once : fometimes the veifels were opened foonei'y 

 fometimes later ; and though frequently delayed 

 very long, tlie fa£t was uniform. In fhort, I re- 

 main under the moil abfolute convi-tlioHj that 

 B 4 the 



