164 Dr. Haigiiton’s experimental Inquiry 
ever they are found, they furnish incontestible proof, that im- 
pregnation either does exist, or has preceded. 
But a proper distinction between past and existing impreg- 
nation can be made only by tracing the phaenomena of recent 
fecundation progressively, and noting the appearances in the 
different stages. I was therefore under the necessity of repeat- 
ing with care several of De Graaf's experiments, in order that 
I might bear testimony to the truth of them, at least as far as 
the results coincided with my own. 
EXPERIMENT. 
Having therefore procured several virgin rabbits in a fit state 
for impregnation, I admitted one of them to the male. Twelve 
hours afterwards it was killed, and on examining the ovaries 
several of the vesicles evidently projected ; they had lost their 
transparency, and were become opaque and red. When punc- 
tured, a fluid of the same colour escaped. I made sections 
through some of them; but at this early period the corpora 
lutea, which are formed by the thickening of the parietes of 
the vesicles, were not very evident. I therefore determined to 
examine them in a more advanced state. 
EXPERIMENT. 
Another rabbit being admitted to the male, I examined it 
twenty-four hours afterwards. The colour of the fluid con- 
tained in the vesicles was similar to that of the last experiment. 
The vesicles projected more evidently, and their thickened pa- 
rietes manifesting the commencement of corpora lutea were 
become more apparent. 
