MR. JONES ON THE IMPREGNATED MAMMIFEROUS OVUM. 
343 
Appendix. 
I think it right to mention that in the Rabbit which formed the subject of observa- 
tion 1, I observed the following other points : 
Having cut off a piece from the ovarian extremity of the Fallopian tube of the right 
side, I put it into a glass capsule, and having laid it open, examined its contents with 
the microscope ; I observed among the numerous shreds of the lining mucous mem- 
brane a small body, transparent, and of a very peculiar shape. Having succeeded in 
transferring it from the capsule to a flat plate of glass, and having removed the shreds 
of membrane, I was enabled to examine it with a stronger power, and see better its 
very extraordinary form and structure, which are well represented in fig. 8. I had 
not a micrometer at the time to measure it, but I think it was about -^th of an inch 
in diameter at its globular extremity. The calculation was made by comparing it 
with an ovum from the ovary. It revolved through the water when the latter was 
put in motion, and in doing so the part a was forced to turn sometimes to the one 
side and sometimes to the other. 
In the next piece of the Fallopian tube of the same side which I examined, I found 
a transparent body not quite round, but prominent on one side, and close by the pro- 
minent point there was a small oval vesicular projection, fig. 9. There was an appear- 
ance of circular lines on it which touched each other at the prominent point ; three 
of the lines were particularly evident, and the prominent point had a brilliant appear- 
ance under the microscope. 
In the next piece of Fallopian tube examined I found a body, fig. 10, which on the 
whole resembled the preceding, but as I might say not so far developed. 
Could the three bodies described have been blighted ova ? They were all about 
-^Vth of an inch in diameter, and therefore corresponding in size to the real ova, 
already described as being found in the same Rabbit. 
Part II . — On the Changes in the Vitellus. 
What I have to communicate in this second part of my memoir is of a much less 
definite character than that which is given in the first part. From the nature of the 
subject it in many cases necessarily consists of inferences rather than observed facts. 
It relates chiefly to the ova of the batrachian reptiles, and is added here merely for 
the purpose of throwing some light on the changes which take place in the yelk of 
the ova of the mammifera, previously to the commencement of the evolution of the 
embryo. 
In approaching this subject the first question which presents itself is : “ When 
does the germinal vesicle of the ova of the mammifera disappear, before or after im- 
pregnation ?” It is known that in birds and reptiles the germinal vesicle disappears 
before impregnation. In the ova of the Frog, contained in the oviduct, and also in 
the more advanced of those contained in the ovary, no trace of the germinal vesicle 
