gu 
the uterine system in women , &c. 
the cause that has been supposed to influence the procreation 
of the two sexes : and to answer effectually, if an answer to 
such a proposition can be thought necessary, the arguments 
adduced by some systematic writers on the subject, but more 
particularly by Mons. Millot, in a recent work, “ on the art 
of procreating the two sexes at pleasure in which he lays 
down distinct precepts for ensuring to parents either a male, or 
a female succession. Most of these systems, and that of the 
latter physiologist more especially, are founded on the ovarium 
and the other uterine appendages being always double ; and 
it is curious to reflect, that however gratuitous such an idea 
might seem, no proof to the contrary has ever been brought 
forward before, to my knowledge. 
The case I have now recorded, however, expunges of course 
for ever from our books of physiology such an hypothesis, and 
leaves us to discover a more plausible reason for this peculiar 
and very interesting feature in the process of generation. 
It moreover puts to rest our doubts respecting a pheno- 
menon of even greater importance, the existence of which, 
every physiologist, who has treated on the subject, with the 
exception of yourself, seems to have been disposed to deny. 
I allude to the fact of the ova of twins, and those of different 
sexes too, coming from the same ovarium ; when, as in the pre- 
sent case, the fimbriated part of the Fallopian tube must ne- 
cessarily remain attached for a considerable length of time 
to the ovarium, so as to allow both ova to pass into the uterus, 
without any union taking place between their membranes at 
any period of their progress through the tube, and afterwards 
coming in contact with a different part of the womb, to which 
they adhere. These circumstances necessarily suppose a dis- 
