198 Mr. Cruikshank’s Experiments 
But the ovaria of quadrupeds often contain vesicles of the hy- 
datid kind ; and it becomes difficult to distinguish between 
what are vesicles, and what are ova. The mark with me is 
this : the ova are inclosed in a capsule highly vascular from 
arteries and veins, carrying red blood. The hydatid vesicles 
are not vascular; at least their vessels carry no red blood. 
The calyx and the ovum, after impregnation, and even before 
it, in the state in which the quadruped is said to be hot , be- 
come black as ink, from the greater derivation of blood ; and 
the ova resemble dark spots : they also come nearer the sur- 
face of the ovarium, so as to pout or project, at last, like the 
nipple in a woman's breast. Some hours after impregnation, 
the calyx and the coverings of the ovaria burst, and the ovum 
escapes ; may fall into the general cavity of the abdomen, and 
form an extra-uterine foetus ; but almost always falls into 
the mouth of the fallopian tube, whose fimbriae, like fingers, 
grasp the ovarium, exactly at the place where the ovum is 
to escape. What the appearance of the ovum was, when 
deprived of its calyx, or when descending the fallopian tube, 
was not known. De Graaf discovered this in the fallopian 
tubes of rabbits, in the year 1672 ; and says, “ minutissima 
“ ova invenimus, quae licet perexigua, gemina, tamen, tunica, 
“ amiciuntur and then adds, “ haec quamvis incredibilia, 
“ nobis demonstratu facillima sunt." 
De Graaf had the fate of Cassandra, to be disbelieved even 
when he spoke the truth ! Dr. Hunter had his doubts ; and 
the great Haller, of whom I have always spoke in the lan- 
guage of Professor Marrhar, “ cujus auctoritas apud me plus 
“ valet, quam auctoritas omnium aliorum anatomicorum simul 
“ sumptorum," positively denies their truth. His words are, 
