On Infiammation i7i FisJies. 229 
their American brethren Physick and Levert, on the probable 
benefit likely to result in the treatment of wounds, from 
substituting metallic threads for those of silk or hemp 
usually employed. They were led to this opinion by ob- 
serving the small amount of irritation sometimes resulting 
from the presence of a metallic substance, such as a bullet, 
in the textures of the body. I was then engaged with 
Professor Simpson in experimenting upon animals, and 
endeavouring with him to collect reasons why the metallic 
thread should supersede the silk one. 
As an instance of how little irritation is caused by metal 
left in living tissues, I instanced the practice of marking 
par, grilse, &c., with wire, and these marks being found in 
the fish after months or years ; whereas, had the material 
of the marks been non-metallic, they would most probably 
have cut or ulcerated out of the tissues. I was told that 
this was no argument, as fish did not inflame — at all events, 
that their tissues did not ulcerate or suppurate — and I was 
referred to the following passage in Macartney's treatise 
upon inflammation : "In neither of the two classes of 
vertebrate animals with cold blood do I believe it possi- 
ble to produce the genuine efl*ects of inflammation. In 
conducting some experiments on the swimming-bag of 
fishes, I was surprised to find that the wound made into 
the belly did not inflame. I was therefore curious to know 
what injuries fishes would bear without producing inflam- 
mation. Having taken some living fishes from the water, 
I introduced pieces of wire beneath the skin and amongst 
the muscles of the body ; the fishes were then returned to 
the water, and on examining them several days afterwards, 
I found that no suppuration had taken place. The tracks 
of the wounds were pale and smooth, and only moistened 
with a serous fluid, and none of the usual appearances of 
inflammation were visible. A very common occurrence in 
fishes is the existence of worms, which perforate the tunics 
of the alimentary canal, without producing any change of 
structure, except an increased vascularity around the per- 
forations. The reproductive power of fishes is confined to 
the fins, which are sometimes regenerated after being lost 
