ON THE FECUNDITY OF MULES. 
269 
To M. Pouchet (of Rouen) are we indebted for what positive 
knowledge we possess regarding the operation of conception, 
he having lifted the veil of mystery in which the act was pre¬ 
viously enveloped. In his beautiful and remarkable work, 
M. Pouchet has demonstrated : 
lstly, That mammiferous animals and the human species 
experience a spontaneous and periodic ovulation. 
2dly, That ova are emitted at determinate periods, readily 
appreciable. 
3dly, That fecundation only happens when the passage of 
the ovum through the sexual canal coincides with the presence 
of the seminal fluid. 
4thly, That fecundation takes place either within the uterus 
or within the horns or vicinous regions of the organ. 
He has also shewn, contrary to the opinion generally enter¬ 
tained, that it is not through the aura seminalis that fecundation 
is effected, but by the thickest of the sperm, that part in which 
is really to be found the greatest number of spermatozoa. 
Now, let us consider the question, whether the ova of the 
mule are susceptible of fecundation; or whether it be that the 
sperm of the horse-mule lacks the property of fecundating. At 
the present day, it is incontestable that the ova of some mules 
are insusceptible of fecundation, notwithstanding their procrea¬ 
tive organs be perfect, and yet all mules may not be impregna¬ 
ble. What, then, are the causes of the infecundity of mules] 
Of this secret we remain ignorant, and in all probability ever 
shall. And as to the prolific property of the sperm of the 
male mule we know nothing for certain, only that the animal is 
in possession of his organs complete. 
Are the horse and the ass more likely to impregnate the 
she-mule than the he-muleis] To this question we may reply 
in the affirmative ; but the ass is more likely to succeed than the 
horse, on account of the greater similarity of nature. Never¬ 
theless, the greater nunber of mules are said to be bred from 
horses covering mare mules, though the reverse may have been 
the case. In regard to mules themselves, we know of no in¬ 
stance where fecundation has taken place. 
In the instances we have related of mules having been known 
to breed, it may be remarked that they almost all have oc¬ 
curred in hot countries, such as Greece, Italy, Spain, Africa, &c. 
The one Lecomte has given us, occurring in the temperate 
climate of the west of France, being an exception. 
We shall terminate this report with a repetition of what we 
know on the subject in question at the present day :— 
1st, That mules, males and females, between themselves, are 
incapable of reproduction—are, in fact, barren—notwithstanding 
VOL. XXV. 0 0 
