446 
DE. W. H. EANSOM ON THE OVUM OF OSSEOUS FISHES. 
evidently identical with the dotted structure. It forms thin layers, of which several 
may be counted. The dottings are dark with light interspaces, or light with dark inter- 
spaces, according to the focus (Plate XV. figs. 22 & 23). 
Besides these minute regular dots, in larger eggs of group 2 there is a darker kind 
of dot, which I will call the stellar dot. It is irregularly scattered over the inner surface 
only, and can only then be seen from the outside, when a lower objective than is used, 
which penetrates sufficiently. They are larger and much blacker than the regular small 
dots, of a stellar form, are wider apart (on an average - 3 ^ ow ")■> but vary much in this 
respect. Examined and measured with a power of X 930, each has a diameter of about 
wooo"- They are in sharpest focus and blackest when a plane rather deeper than the 
true inner surface is in focus, and with that surface in focus they look like stellar-shaped 
pits. On focusing they act like bodies of low refractive power. At the cut edge they 
may be seen to pass radially about two-thirds into the substance of the yelk-sac, gra- 
dually coming to a point and ceasing. They do not look like spaces at the cut edge, as 
do the fine regular dots. 
The buttons may be well examined in unripe ova, especially those nearly ripe. They 
are attached to the outer surface of the yelk-sac by a bright, highly refractive point, 
from which radiate along their under surfaces to the periphery, little folds of the sub- 
stance, which is clear, homogeneous, soft, and easily distorted, by contact, in consequence 
of its adhesiveness. 
I counted the number of buttons on five small eggs of group 3, and on the average 
found 80 to each. The average number on each yelk-sac of nearly ripe ova, or group 1, 
is 207, a result of five countings. In ripe deposited ova I could not prepare the yelk- 
sac so as to count them, on account of the readiness with which they became detached, 
by adhering to external objects; but there is no reason to think the number increases 
after the stage of group 1 . I think it probable that they are organs of adhesion, and 
serve to fix the egg. 
d. The method of staining tissues , so strongly recommended by Dr. Beale, was tried 
with reference to its importance as a test of germinal matter, a term which I assume to 
be synonymous, or nearly so, with protoplasm. 
If a fragment of ovary be digested in the carmine solution* for half an hour, and then 
washed with the acetic acid glycerine, it will be found to be irregularly and unequally 
dyed, this irregularity affecting the ovarian stroma, the yelk -sac, and the yelk. The 
tissue of the ovary is softened to an almost viscid consistence ; whether an effect of the 
ammonia or of the acetic acid I did not stop to ascertain. 
After twenty-four hours’ digestion in the carmine solution the stroma is deeply dyed, 
but less so than the yelk of the youngest ova. Those parts of the ovarian tissue which 
are thickest, such as vessels, have the deepest tinge ; the films of connective tissue show 
no colour, perhaps on account of their extreme tenuity and translucency. 
In the fragment which had been digested for half an hour, the minutest eggs showed 
* This was prepared according to Dr. Beale’s formula. 
