HEREDITARY DISEASES OF HORSES AND CATTLE. 285 
Australia, and we understand that there, as in England, he 
got a curby race. 
Mr. Cartledge, V.S., stated, at a meeting of the Veterinary 
Medical Association a short time since, that a thorough-bred 
stallion, called “ Fifty-three / 5 begot foals in his locality, and 
of these no less than twenty- six became afflicted with curbs 
before they were twelve months old, and yet this horse had 
no symptom of the disease. At the same meeting, Mr. 
Varnell, V.S., stated, that an entire horse, called “ Monarch / 5 
had served mares in the county of Norfolk for some years, 
and on his colts being broken — some at three, and others at 
four years old — the majority were affected with spavins, 
splints, and ring-bones, yet he himself was entirely free from 
any of these diseases. 
These curious exceptions to the law by which hereditary 
diseases are supposed to be governed, may be referred to the 
condition last mentioned, of the revival of a hereditary like- 
ness absent in one or more generations, and familiarly known 
to breeders under the term cc breeding back. 5 ’ The explana- 
tion may not be considered a satisfactory one, for it must be 
confessed that we have but very obscure notions of some of 
the laws which regulate variation in animals. That such laws 
do exist appears highly probable from the numerous instances 
of the constant recurrence of similar phenomena under 
given circumstances, which seem to preclude their depend- 
ence upon mere accident, and the most striking one is the 
law which governs the extent to which variation is allowed 
in the animal economy. There appears to be a limit beyond 
which change or variety cannot be induced, the original type 
of the species being ever present, and in constant opposition 
to their continued progress. This is particularly observed 
in instances where great refinement in breeding is prac- 
tised. When the stock has been got up to what is com- 
monly considered the highest perfection, a tendency to 
degenerate, or return to the original standard, is sometimes 
observed, and the greatest difficulty is experienced in com- 
bating against this inherent property. Many a breeder can 
certify to this, that the nearer he approaches perfection in 
breeding, the greater is the danger of retrograding. But 
that which is considered perfection with reference to man, 
such as early ripeness of bone and muscle, with disposition 
to acquire fat — qualities which eminently characterise our 
high-bred flocks and herds — are, after all, but a state of de- 
gradation with reference to nature, since these extraordinary 
characteristics could never arise or be perpetuated in a wild 
state under any imaginable combination of accidents. 
