il. SEMINAL VERMICULIy 45 
evaporation in the tube with the {topper touching 
the femen ; indeed it was impoffible, as no vacui- 
ty was between them; but the femen in the 
other tube had evaporated. The infide of the 
glafs and the end of the ftopper were covered with 
a thin pellicle, formed of a very tran{parent fluid, 
which could be nothing but the more fubtile parts 
of the femen volatilized by heat. The quan- 
tity was diminifhed, which could not be other- 
wife, and it was a little thicker ; neither of thefe 
circumftances was remarked in the other tube. 
Both the fluids were examined with a magnifier : 
the vermiculi were alive where there was no evapo- 
ration ; in the other tube all were dead. Thus itis 
evident, the folar heat does not kill the vermiculi; 
but that their death is occafioned by fome noxi- 
ous quality imparted by it to the femen, either 
confifting im that thicknefs, or fomething elfe de- 
rived or generated on the occafion, which alfo 
correfponds with the nature of animals that are 
injured and perifh, if the ambient fluid in which 
they live, aerial or aqueous, begins to alter and 
fpoil. 
It fhould likewife be explained how two degrees 
of heat, equally intenfe, can produce fuch oppofite 
effets: for, the immediate ation of funfhine 
kills the vermiculi, while that of a heated apart- 
ment does them no injury: but my obfervations 
have 
