XXXV 
American Poifon called Ticunas. 
is warm. A humour, or the blood’s being affedled by a poifon* 
may by degrees produce, in cold-blooded animals, diforders flill 
greater than thofe which may be caufed by flopping the cir- 
culation. 
By death taking place immediately on introducing the poifon 
into the blood, we may be induced to fufpedl, that there exifls in 
that fluid a very adlive, fubtle, and volatile principle, which 
eludes the acutefl fight, and even the microfcope itfelf. This 
principle may on this hypothefis appear neceffary to life, and 
againfl this principle the poifon may be fuppofed chiefly to 
diredl its operation. 
That there really exifls in the blood a very adlive and volatile 
principle, may very well be fufpedted from feeing that the poi- 
fon of the viper prevents the coagulation of the blood when it is 
drawn from the veffels, whilfl, on the contrary, it produces a 
coagulation of it within the veffels. It may be fuppofed, that 
fomething evaporates from the blood when it is drawn out, 
which exifls in it while within the veffels. On this hypothefis 
this adlive and vital principle may be confidered as the refult of 
the whole animal oeconomy, not excluding the nerves which 
may moflly contribute to it. But all this is only mere con- 
jedlure, more or lefs probable, and unfupported by experiment* 
We ought to abide by fure fadls, let the mode of explaining 
them be what it may. Now thefe fadls are, that the American 
poifon does not adl on the nerves, and that its adlion is intirely 
on the blood. 
Before my experiments no perfon would have doubted but 
that the adlion of the American poifop was immediately on the 
nerves. All the external figns declared it to be fo. Thefe figns 
then are equivocal, and they are falfely adopted by phyficians 
for the certain proofs that a difeafe is purely nervous. All thefe 
fymptoms may exifl without the nerves being in the leafl af- 
fedted : the alteration of the blood alone is fufficient to produce 
them in a moment. The principal phyficians have attributed 
the difeafe produced by the poifon of the viper, and by the Ame- 
rican poifon, to an alteration in the nerves ; it belongs to them 
now to examine, whether other difeafes, fuppofed generally to 
E 2 be 
