NOTES AND MEMORANDA. 
45 
which have not been exposed to the possibility of fecundation. The 
fact was mentioned by Bischoff and E. Leuckart, and M. Moquin- 
Tandon has recently communicated some analogous and more detailed 
observations to the Academic des Sciences. The first phases of seg- 
mentation were distinctly observed in the egg dropped by a female 
frog which had been kept in confinement for about four months, and 
seclude^ from all possible intercourse with the male. In the ovule, 
first two large vertical fissures were seen, and then a horizontal fissure. 
The segmentation then proceeded in a less orderly way, the vitelline 
spheres multiplying irregularly, and becoming of unequal size. The 
process was more rapid than in fecundated eggs which were allowed to 
develop at the same temperature. Only a small number of the ova 
presented this evidence of commencing development; the majority 
died without any sign of segmentation. In all cases the phenomena 
soon ceased, the spherules produced separated, and the whole mass 
began to decompose. Sometimes death occurred after the division 
into two or four segments, sometimes at a more advanced period, but 
the ovule never assumed the mulberry look. M. Moquin-Tandon 
points out that the observation establishes incontestably that the ova 
of vertebrata not impregnated by spermatozoa may pass through the 
earliest stage of development in certain conditions, the exact nature of 
which is at present unknown. These facts, says the ' Lancet/ may be 
placed beside those of the same kind observed by Bischoff on the sow, 
by Hensen on the rabbit, by Agassiz and Burnette on fish, and 
especially with the remarkable fact observed by Oellacher that in 
fowls kept far from a cock unfecundated eggs underwent segmentation 
in the interior of the oviduct. 
NOTES AND MEMOEANDA. 
American Photographs of Blood-disks. — Mr. G. Gulliver, F.E.S., 
who is known to be the greatest living authority on the subject of 
blood-corpuscles, has sent Us the following note. We may mention 
that we ourselves have received a photograph from Dr. Eichardson, of 
America, which, as mentioned in a former number, exhibits the dif- 
ference between the blood of man and the pig with great distinctness. 
" Through the courtesy of Professor Thomas G. Wormley and Dr. G. 
Eichardson, I have received several photographs of mammalian red 
blood-corpuscles compared with those of man. In each specimen, on 
a single slide, the corpuscles of the human subject are shown in one 
microscopic field of vision with those of brutes. Thus the human 
blood-disks are compared with those of the pig, cat, dog, &c., and in a 
very instructive manner ; especially as a group of such minute bodies 
displays better their differences of size in different species than a 
single corpuscle of each of them. I know not that such preparations 
of these corpuscles have been made in Europe, but anyhow these are 
very creditable to American microscopy. Objection might be taken 
