196 Dr. Haighton's experimental Inquiry , &c. 
required a more elaborate exertion of the formative powers of 
these parts to produce what might figuratively be called the 
nucleus of a foetus, than to go on and complete the work. 
But this remark applies only to the rabbit ; for in the human 
female, abortions at the third month clearly prove that the 
evolution of the foetus has been perfected some time before. 
Such an obvious difference cannot fail to impress our minds 
with doubts and distrust, whenever we are drawing inferences 
from analogical reasonings : but to trace the formative pro- 
cess, of nature through this work, and to compare her progres- 
sive advances in the different periods of utero-gestation, are 
foreign to the design of this essay. 
It remains then for me to beg pardon for having so long 
trespassed on the patience of this Society. 
