608 
ON BREEDING. 
4 4 r 
method of detecting each adulteration. This has not yet been 
included in the instruction of the veterinary pupil. There are no 
lectures or publications which afford this information, indispen¬ 
sable to the veterinary student, and exceedingly interesting, and 
abounding’ with many a useful hint to the human practitioner. 
I have spoken likewise of illustrating certain portions of phy¬ 
siology by philosophical and chemical experiments. I will be 
careful that this most seducing method of instruction shall not 
carry us too far; but the striking effect of oxygen on freshly 
drawn venous blood may explain, and indelibly stamp on the 
memory, the change which the blood undergoes in respiration— 
an experiment or two in mechanics may elucidate the percussive 
action of the heart on its contents—a reference to some simple 
principles of hydraulics may elucidate the circulation of the 
blood through its various vessels—the effects of galvanism may 
beautifully illustrate the various modifications of nervous influ¬ 
ence in respiration, digestion, and muscular motion—the laws 
of optics may render plainer the mechanism of the eye; and the 
theory of the lever may render evident to every capacity the re¬ 
lation between conformation and action, and the perfect adapta¬ 
tion of the various parts of our domestic animals, and of the 
horse particularly, to the purposes for which this were designed. 
[To be continued,] 
ON BREEDING. 
By Mr. Karkeek, of Truro . 
I 
[Continued from p. 493.] 
u Nothing in the animal economy,” said Galen*, “ is ruled by 
invariable laws, or can be subject to the same accurate results 
and calculations as an inanimate machine.” All domestic ani¬ 
mals have a tendency to degenerate, or to regain the original 
stamp which nature assigned them; but this inherent tendency 
to change is counteracted by cultivation, and by selecting indi¬ 
viduals to breed from; which is opposing, in fact, art to art. 
The same circumstance is seen in vegetables: the golden pippin 
of our gardens would soon be converted info the austere crab of 
the woods, and the numerous varieties of the plum would 
quickly degenerate to the native sloe, were we to attempt to 
propagate them by seed instead of preserving their variety by 
* Nil est in corpore viventc plane sinccrum. 
