DK. W. H. RANSOM ON THE OVUM OE OSSEOUS EISHES. 
485 
still imperfectly distended with water, contracted slowly, resembling eggs three or four 
minutes after impregnation while the breathing-chamber is forming. The eggs of the 
uppermost layers contracted vigorously, and quite as much so as those of the control 
experiment 1. Nearly all had their proligerous disks entirely separated and broken into 
masses. The intermediate layers of ova in the beaker exhibited the formative yelk con- 
centrated, but not at all lobulated ; from which it would seem that the tendency of the 
discus proligerus to lobulate, and to be pinched off in portions or as a whole, like the 
rhythmic contractions, depends on a free supply of water as one of its conditions. The 
same may be said of the concentration of the granules of the formative yelk, and I think 
also of the tendency of the inner sac to rupture. Seventy-two hours after, the contrac- 
tions were as vigorous as ever in the clear yelk-balls of the upper layers of eggs ; the 
discus proligerus was entirely detached in all. 100 hours after, contractions had ceased, 
the water had a very faintly milky aspect, and the eggs were opaque. Three days later 
the water drawn off was not foetid, it reacted faintly acid, and gave a slight precipitate 
with barvta-water. 
Experiment b . — The last experiment was repeated, with one part of unimpregnated 
ova to about three parts of water. The contractions were observed twenty-seven, forty- 
nine, and seventy-two hours afterwards, and found to be as vigorous as those in experi- 
ment a, or in the control experiment 1. They were seen only in the eggs of the surface 
layers, which alone had imbibed water freely. 100 hours after, and three days later still, 
they resembled experiment a. The fact that water was not absorbed freely, except by the 
upper layers of these eggs, deprived the experiment of a part of its value, as the propor- 
tion of actively contracting eggs to the water had no definite relation to the numbers 
used, and could not be determined. 
Experiment c . — The experiment was repeated, using equal parts of unimpregnated 
eggs and of water. At twenty-seven, fifty, and seventy-six hours after, the rhythmic 
contractions of the yelk were as vivid as in experiment a or in control experiment 1 ; 
but the discus proligerus was less lobular, and not so often detached. 104 hours after, 
all the eggs were opaque. 
In this experiment mechanical disturbance was employed at first, to ensure a nearly 
equal action of water on all the eggs, but they were not quite fully distended, although 
nearly all the water was taken up ; from which we may conclude that normally the eggs 
imbibe about their own bulk of water. 
Experiment d . — The same as the above, using two parts of unimpregnated ova to one 
of water. Very few eggs of this experiment imbibed water, and those did so imper- 
fectly. The rhythmic contractions were feeble, the formative yelk scarcely lobulated 
at all. The lowest layers did not visibly absorb any water, efface their indentations, or 
concentrate the formative yelk in the slightest degree. At 104 hours after, they were 
opaque. 
Experiments were then attempted to be made in a similar manner with impregnated 
eggs, but being unable to insert a tube into the male fish, I passed a piece of ripe testis 
