DE. W. H. EANSOM ON THE OVUM OE OSSEOUS EISHES. 
473 
capsule, in tap-water and lightly covered. At thirty minutes and at forty minutes after 
impregnation, the contractions were observed to be normal ; at l h 10 111 they were almost 
limited to the neighbourhood of the germinal disk, and its surface directed towards the 
food-yelk; at two hours cleavage began; at 2 h 40 m progressing, the “ Faltenkranz” 
distinct ; at 3 h 30 m the second cleft commencing ; at five hours complete ; at eight hours 
there were thirty-two cleavage masses ; at twenty-four hours the germinal mass was com- 
posed of minute cell-like corpuscles. 
Control experiment 2. — About six ova were impregnated, and kept in a lightly covered 
cell in tap-water. At thirty-five minutes after impregnation they were contracting 
normally, at 2 h 15 m were about to cleave, at 3 h 30 m the first cleft was completed, and 
the second about to begin ; at twenty hours after, the germinal mass was a cluster of 
corpuscles having the general aspect of cells. 
Experiment 1. — Into a similar cell, five minutes after impregnation, an equal number 
of ova were put in ordinary aerated distilled water. The cover was sealed with hot wax 
and lard, an operation which lasted about two minutes. The eggs were then compared 
with their control ova, at thirty minutes, at forty minutes, at l h 10 m , at two hours, at 
2 1 ' 40 m , at 3 h 30 m , at five hours, at eight hours, and at twenty-four hours after im- 
pregnation, and were on each occasion found to be progressing equally with them. 
Accidentally one or two of these eggs were injured, so that the inner sac broke, and 
partially emptied itself, but cleavage went on in an irregular manner, although with a 
rapidity equal to that observed in uninjured ova. 
Experiment 2. — An equal number of ova, twenty-five minutes after impregnation, 
were put into a similar cell, in distilled water which had been well boiled, and the cover 
was sealed as before. At forty minutes, at one hour, at two hours, at 3 h 30 m , and at 
twenty hours after impregnation, they were found to be progressing, equally well with 
their control eggs. 
Experiment 3. — The same as the above, using water in the cell which had been satu- 
rated with hydrogen after having been boiled. At forty-five minutes, at one hour, at l h 
55 m , at 2 h 15 m , at 3 h 30 m , and at twenty hours after impregnation, they were also found 
to be progressing, like the eggs in the control experiment. 
Experiment 4. — The same as the last, using distilled water impregnated with oxygen. 
At forty minutes, at l h 10 m , at two hours, at 2 h 40 m , at five hours, at eight hours, and 
at twenty-four hours after impregnation the ova were examined, and found to be quite 
like their control ova. 
Experiment 5. — The same as the above, using water which had been moderately 
charged with carbonic acid, after having been well boiled. Forty minutes after impreg- 
nation, immediately after the cell had been sealed, the yelks were seen in the dumbbell 
form, and under observation the sulcus was effaced without travelling on, the yelk- 
ball becoming round, even the germinal mass ceasing to be prominent. For some mi- 
nutes there was no visible movement, but afterwards, by imperceptible degrees the 
germinal mass was slowly reprotruded from the surface in a nipple-shaped and rather 
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