ON BREEDING. 
The vegetable and animal worlds present much similarity vvitli 
respect to the generation of offspring; with this difference—that 
the extent to which mules are permitted to exist in the animal 
world must depend on their instinctive feelings; whilst an un¬ 
restrained and unlimited intercourse between plants is carried on 
by the incidental operation of winds and insects. Linnseus was 
of opinion that hybrids were abundantly formed : if then, such 
had proved capable of affording offspring, all traces of genus and 
species must .surely long ago have been lost in oblivion, since 
every species of plant under such circumstances, must, of neces¬ 
sity, continue to assume variations of form, had not Nature, in 
order to preserve the original species entire, wisely stopped, in 
instances of deviation, the powers of propagation. Animals of 
the same species, in a state of freedom, are drawn by an imma¬ 
terial tie, an instinctive tendency, to propagate for the continua¬ 
tion of their kind; and they appear to have an instinctive 
aversion to an union even with those that are most nearly allied, 
such as the horse and the ass, the dog and the wolf, the hare and 
the rabbit: but when by confinement, and by the assistance of 
stratagem, they are brought to copulate, we believe that their 
offspring seldom or never generate; but if they did (for we never 
have yet seen any thing like satisfactory evidence to prove it, 
two or three instances excepted,) we should consider it, with 
Juvenal, as a prodigy : 
Egregium sanctumque virum si cerno bimembri 
Hoc monstrum puero, vel micmti sub aratro 
Piseibus inventis et fceta compare mulcc. 
We must, therefore, continue to believe, notwithstanding there 
is so great a dissimilarity in the appearances of the different races 
of horses as to permit their dislocation into separate genera, that 
their indiscriminate and sexual intercourse, and consequent pro¬ 
duction of offspring capable of propagation, is alone sufficient to 
prove all the varieties to have descended from the same parent 
stem; the power of producing, by copulation, a succession of 
similar beings, being considered by naturalists as the surest 
criterion of determining the different species. 
[To be continued.] 
SPECIMENS OF FIVE MONTHS’ VETERINARY 
STUDY. 
The following facts we have extracted from the spirited letter 
of one of our esteemed Correspondents. We agree with him, that 
