DK. W. H. RANSOM ON THE OVUM OF OSSEOUS FISHES. 
435 
if eggs be ruptured with no other fluids than the adhering maternal secretions, such as 
the serum, or the alkaline viscid layer ; and care being taken to note the position of the 
escaping currents, it seemed as if the acid food-yelks had a similar effect. 
These changes, so common in protoplasmic matter, wherever met with, give rise to the 
suggestion that they may be due to the separation of two immiscible fluids, by the con- 
tact of a third, from a previous state of feeble combination. The lilac or faint blue tint 
of the vacuoles may be an optical effect of contrast, as I produced a similar appearance 
by shaking together water and yellow fat, but, as the depth of the lilac tint is not 
in the ratio of the depth of the yellow, I am not certain on this point. That I am justi- 
fied in calling them droplets, is shown by the fact that they sometimes fuse together. 
The granular basis, which, besides the yellow droplets in a granular condition, forms 
the formative yelk, is exhibited best by the action of water, w’hich, while it causes the 
latter to disappear gradually while vacuolating, makes the former at once become darker 
and more distinct, and does not cause its ultimate disappearance. 
The homogeneous matrix of the cortical layer contains also a peculiar form of albumen, 
which water precipitates in fine molecules, and which I shall have to speak of as albu- 
men b. 
The yellow droplets disappear also with vacuolation in a solution of sal-ammoniac, 
although less rapidly than in water. A weak solution of acetic acid acts on them some- 
what similarly. A weak solution of potash rapidly dissolves them, and those of them 
which are in the granular condition are similarly acted on by these reagents. 
The larger part of the granular substance of the cortical layer, rendered darker by 
the action of water, is not dissolved by sal-ammoniac or by dilute acetic acid. These 
agents cause a precipitate to appear, of dark granules of a coarse kind, and make the 
whole layer solid, by coagulation. A weak solution of potash also leaves a granular 
solid layer after dissolving the yellow droplets. 
That portion of the granular matrix which is dissolved by sal-ammoniac, is finer than 
the substance precipitated by it, and if after this reaction a solution of acetic acid be 
added, a further precipitate of very fine granules is formed, which is due to the presence 
of albumen b. The finer granular deposit caused by the contact of water is easily dis- 
solved by the solution of sal-ammoniac, not by acetic acid. 
Thus it is possible to distinguish in the formative yelk (1) part of the substance of the 
inner sac, (2) the matter of the yellow droplets and the granules of the same material, 
(3) the granules darkened by the action of water and not dissolved by the alkaline chlo- 
rides, (4) the smaller oil-drops — all existing as separable substances already formed. 
In solution or otherwise not optically separable, (1) the albumen b, (2) the matter so 
largely precipitated by the sal-ammoniac. 
No trace of a germinal vesicle or of its contents could be found after the most careful 
and repeated searching. 
The food-yelk forms the chief mass of the egg. It is a thick fluid drop, covered by 
the formative yelk, colourless, transparent, and without visible contained particles, ex- 
