57 



It appears to me that the most useful practical inference that 

 arises out of this investigation, is an inquiry how far human 

 beings are subject to diseases produced by similar causes ; and 

 we may also ask, may not some of those diseases which attack 

 people very suddenly, and without any appreciable cause, be oc- 

 casioned by something similar to that which produces this disease 

 in flies, the extraordinary minuteness of the germs causing such 

 maladies occasioning them to elude our keenest observation ? 



TRANS. MIC. SOC. VOL. m. 



