478 DR. W. H. RANSOM ON THE OVUM OF OSSEOTJS FISHES. 
The formative yelk in these eggs breaks up ultimately into a formless, dark, granular 
mass. 
The fecundated eggs continued to. contract and oscillate vividly during the progress 
of the cleavage, and often, where the sulcus was strongly marked, the surface of the 
inner sac was beautifully wrinkled, like a ripple upon water. Fifty hours after fecun- 
dation the contractions were more active than in the unfertilized eggs, which then were 
seen to have vibriones upon them, appearing to be liable to decomposition earlier than 
fertile eggs, and to suffer in consequence some diminution of their contractility. The 
fertilized eggs, after fifty hours, have a germinal mass composed of polygonal cell-like 
corpuscles, on the surface of which I failed, with a power of X 250, to detect any trace 
of ciliary action. 
To ascertain, if possible, in what part of the yelk-ball the contractile property resided, 
I ruptured, by pressure, one which had been fecundated fifty hours, the contractions 
being at the time vigorous. 
An irregular shred of the inner sac was retained within the crushed yelk-sac, and a 
pouch of the former, filled with food-yelk, projected from the rupture in the latter. 
Very active contractions were seen 1-|- hour afterwards in both of these, causing a to-and- 
fro movement, during which the pouch was alternately protruded and retracted from 
the opening in the yelk-sac ; and the shred of inner sac, which had partial attachments, 
moved right and left, each time, seeming to alter its form somewhat : the rapidity of 
these motions was much greater than that seen in unbroken eggs. I counted on the 
shred three contractions, each causing a right and left motion in one minute, and a 
point on this shred passed through in ten seconds. For six hours longer contrac- 
tions continued in this ruptured egg. 
The torn shred seen moving within the broken yelk-sac could scarcely have been other 
than a portion of inner sac, and it had precisely the same appearance, examined with 
X 250. At this stage of development of the germ there is no differentiation of parts, 
and no contractile property, and on its mass of cell-like corpuscles, as already stated, 
no cilia or ciliary movement could be found. 
It was found impossible to repeat this observation exactly, at least so far as regarded 
the happy accidental position of the torn shred of inner sac, although a number of 
attempts were made. However, I often found escaped and projecting pouches of the 
inner sac containing food-yelk, over the surface of which contractile waves passed, 
with varying degrees of rapidity; and in one instance, while endeavouring to stain an 
unimpregnated egg with an extremely weak ammoniacal solution of carmine, these 
waves were seen, an hour after it had been crushed, moving with considerable velocity. 
The pouch of the inner sac was in this instance so large, as to contain the greater 
part of the food-yelk of the egg. The contractile waves had a certain rhythm, but not 
a very regular one ; two or more waves sometimes coexisted, and as they travelled along 
they proceeded in the same or opposite directions, and then if two met, a very deep 
angular sulcus resulted, which showed a tendency to recur at the same spot. One of 
