89 
CONCEPTION, &C. OF THE MULE. 
authenticated it. And M. de Nanzio himself, anxious for some 
intelligence on the matter, went to the place towards the end of 
May 1845, and saw the mule in question together with its little 
one. 
We may safely affirm then, that, as mules have bred once, they 
may do so again, and that we have no right to regard them as al- 
together sterile ; and that, as a consequence, Pliny was in error 
when he asserted that animals issuing from two species become a 
third species, differing from either parent, and incapable of repro- 
duction. And so, as little reliance must be placed in the judgment 
of others, who, blindly credulous of what has been said by the 
Roman naturalist, re-echo his words, and say that the mule cannot 
breed. * 
Buffon followed Aristotle in the same doctrine, supposing that 
any commerce between male mulet and female bardot, or even be- 
tween male and female of the same cross, would prove unpro- 
ductive ; and for the reason, that two natures came together already 
altered by generation. 
This assigned sterility in the mule species has led to an exami- 
nation into the causes of their barrenness. And M. Hebenstrach, 
a believer in their absolute sterile nature, pretends to have disco- 
vered the causes of it, alleging that it proceeds from the semen 
of the mule wanting the spermatic animalcules ; — from the circum- 
stance of the ureter opening into the vagina, whereby, whenever 
the animal urinates, the sperm is washed away ; — from the uterus 
being slender and pellucid, compared with those of other animals, 
and consequently incapable of supporting the weight of the embryo ; 
— from the ovaries not containing any transparent vesicles com- 
monly called ova ; — lastly, from the Fallopian tubes being too 
narrow. 
These reasons, says M. de Nanzio, have been refuted by 
M. Brugnone, who maintains that the external genital organs 
of the mule present no imperfection, that the spermatic vesi- 
cles contain sperm in abundance, and that the ureters open no 
way differently from those of other solipedes, &c. Notwith- 
standing this, however, we have regarded it as our duty to 
institute fresh inquiries into these matters, and principally as 
regards the mule ; we taking another view of the question, and 
thinking that the mule could hardly be sterile without some im- 
portant defects — either, first, in the organs producing the ova ; or, 
secondly, in the tubes destined to conduct the ova into the organs 
of gestation ; or, thirdly, in the conformation of the womb. 
In comparing the ovaries of the mule with those of the mare, we 
cannot say we have discovered any especial difference. The vesi- 
cles of Graaf are equally visible in one and in the other. But the 
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