[ 47^ 1 
ner as Horns and Nails, and other like fubftances. The 
pain proceeds from the compreffion of the Nervous 
parts, as that in Corns, which when any thing hap- 
pens to pinch them, is very acute, and the lividityfrom 
an obftruftion of the progrefs of the Blood. If the d^ 
coloration was the effefi: of any Cauftic Salt, an Efcarr 
would foon enfue, but the blacknefs of the Cancers 
Jafts many years. It is more reafonable than to think 
the difficulty the Blood finds in its paffage, makes it 
ftop in fome places, where lofing its fluidity, and be- 
coming thick, it makes the skin which covers the Can- 
cer appear black and livid , and this blacknefs is 
obferved round the Horns of Animals at their firft 
eruption. 
The Ulceration proceeds either from the burding of 
the Teguments by the encreafing fwelling, or their 
exefion, by the corruption of the ftagnacing Blood. 
But their incurability arifes from an indilpoficion of the 
Fibres of the Skin , to unite themfelves with the Can- 
cerous Lump. From this account it is plain Schirrofi- 
ties, StrHm£^ which confift of Liquors ftopt by their 
Vifcofity, or coagulated by any Acid, and Folypus, 
where the Veflels keep their order and diftribution, are 
efientially different from thefe carcinomatous fvvellings, 
but when theftrudure of the Veflels is once dedroyed, 
and they degenerate into a hard indiflbluble lump, ca- 
pable of fliooting out, they lofe their former nature, 
and become Cancerous. 
Having thus prefented you with his Idea of the Na- 
ture arid Caufes of Cancers, he proceeds to the Prog- 
noftick and Cure. True Cancers he affirms are feldom 
extirpated with" fuccefs^ and the operation would be 
lefs in repute, if Strum^^ fchirrous, and other Tumours 
were not frequently miftaken for them. Mr Gmdron 
only thinks thofe can be extirpated, vvhofe Bafis ends 
at once, and which do not fend ftrings to the neigh- 
E e e e bouring 
