i86 Dr. Haighton’s experimental Inquiry 
form be essential to impregnation, here has been an oppor- 
tunity for such contact during the space of six hours ; but it 
has not been sufficient to advance the procreative operations 
further than happened in those experiments where the tube 
had been divided before coition. Let us then for a moment 
suppose that the interval be lengthened, in order to allow a 
better opportunity for producing the full effects of impreg- 
nation, by exposing the ovary a longer time to the stimulus 
of the semen. 
EXPERIMENT. 
I cut through the left tube of another rabbit twelve hours 
post coitum, and examined the parts on the fifteenth day. 
There were four corpora lutea with the same number of foe- 
tuses on the right side, and three corpora lutea without foetuses 
on the left; so that twelve hours supposed exposure to semen, 
had made no sensible advances in the procreative operations 
on the mutilated side. 
EXPERIMENT. 
The same operation was repeated twenty-four hours post 
coitum. Corpora lutea were found in both ovaries, but foetuses 
only on the perfect side. 
Now I observed in one of the experiments related in the 
former part of this essay, that the vesicles of the ovaries when 
examined forty-eight hours post coitum , were extremely pro- 
minent ; they appeared as if going to burst : it is but reason- 
able then to admit, that at this time they must have received 
their full measure of stimulus ; and if one of the tubes was di- 
vided in this state of things, the result would be more decisive. 
