Lamenesses of Sheep and Lainhs. 
387 
from which the bones are developed in the foetal state. Minute 
vessels shortly shoot into it, rendering it ruddy, firm, and clastic. 
By and by, earthy matter is laid down — the cartilage becomes 
ossified. But the exudation matter is poured out, hardened, and 
ossified, not only between the severed edges of the bone, but 
also extending between the periosteum and outer surface of the 
bone for a little way above and below the fracture — thus forming 
an encasing ring for the strengthening and support of the mend- 
ing bone, and preventing the displacement which the slightest 
motion would otherwise produce. Is not this a most beautiful 
and bountiful provision of nature? The broken bones of the 
lower animals, thus held together and strengthened by " ensheath- 
ing callus," make a safe and speedy union, and suffer compara- 
tively little from the motion to which, during recovery, they are 
necessarily subjected. But nature, ever bountiful, is never 
lavish. She denies the encircling callus in most fractures of the 
human bones, but endows man with reason, and leaves him in 
this, as in otlier matters, more dependent than the lower animals 
upon the assistance of his fellow mortals. But the supporting 
callus, when really necessary, is freely given. The ribs of man 
cannot, like the other bones, be kept at rest. Respiration 
cannot wait till bones unite ; and here, accordingly, " ensheathing 
callus " is poured out, helping and hastening the process of 
repair. Again, where frequent movements have frustrated the 
normal union of broken parts, nature occasionally, even with 
other of the bones of man, makes use of this simple and beauti- 
ful means of retaining the parts in apposition and accomplishing 
their union.* 
Rheumatism. — Most of the domesticated animals are subject 
to rheumatism, and it exhibits a great similarity in all of them. 
It is a blood disease, characterised by the accumulation of acid 
matters in the vital fluid. The accompanying fever is generally 
acute. The inflammation attacks particularly organs of a fibrous 
structure, and manifests a strange disposition to flit from one 
part to another. Amongst sheep it frequently affects the muscles 
of the back, involving especially their tendinous sheathing. It is 
accompanied by much pain, great stiffness, and unwillingness to 
move, with all the symptoms of acute fever, namely, a hot mouth, 
cold extremities, a firm, hard, and somewhat accelerated pulse, 
with quickened breathing and arrested secretion. In fact the 
animal has lumbago. After a few days the malady not unfre- 
quently changes its site, the muscles about the neck and shoulders 
become involved, whilst those originally affected are much 
relieved. Again the symptoms will abate, when suddenly the 
* See ' Lectures on Surgical Pathology,' by James Paget, vol. i. p. 251. 
