DR. W. H. RANSOM ON THE OVUM OF OSSEOUS FISHES. 
451 
by water. This substance, which I have spoken of as albumen b provisionally, I have 
thought worthy of a somewhat more detailed examination, because it appears to be 
present in some proportion in the yelk of all the osseous fishes which I have been able 
to procure, and it, or a closely allied substance, is a constituent of the yelk of frogs and 
birds. 
Its ready precipitation by water suggests the notion that the inner sac may possibly 
be formed by a gradual hardening of the surface of the yelk, through a chemical action 
of the surrounding medium, which in the ovarian ova would be an exudation from the 
blood. Certainly the inner sac was noticed to become firmer and more distinct in eggs 
which had been long exposed to the action of water. Whether this property of albu- 
men b has any part in the formation of cell-walls is an interesting speculation, but one 
to which these observations give no direct support. Be that as it may, a substance 
easily precipitable by water is, I believe, very widely met with in animal protoplasms, 
and the firmer limiting surfaces, which in the protoplasmic balls of rapidly growing 
structures are the only representatives of true cell-walls, may owe their formation to its 
precipitation. 
a. Fluid albumen b . — The food-yelk of the salmon is a thick fluid albumen, entirely pre- 
cipitable by water in excess, if free ova be used ; if ripe ova in ovario be used, a small pro- 
portion of ordinary albumen remains dissolved in the supernatant water, and may be coagu- 
lated by boiling, and nitric acid ; but this is derived from the vascular tissue of the ovary. 
The characters of this albumen, when in solution, may be studied in the entire egg, or 
in crushed eggs treated with water, in too small a proportion to precipitate all the albumen. 
It then is coagulated by boiling, nitric acid, hydrochloric acid, alcohol, and ether. 
Dilute acetic acid coagulates it, and stronger acetic acid redissolves the coagulum, after 
which water will not precipitate it, nor will carbonate of potash added to alkalinity. In 
the alkaline solution mineral acids do not cause a precipitate unless heat is applied, nor 
does boiling without a mineral acid coagulate it. The acetic acid solution is, however, 
precipitated by yellow prussiate of potash. 
b. The solid albumen b . — In the solid state this albumen, obtained by precipitating it 
with water, is white, finely pulverulent, composed of immeasurably fine molecules ; while 
moist, it gives an acid reaction, after the most prolonged washings, short of decomposi- 
tion ; part of it always passes through the filter on account of its fineness and the 
absence of dense flocculi. 
A strong solution of chloride of ammonium dissolves it, and the solution is not repre- 
cipitated by alcohol unless boiled, and only imperfectly coagulated by boiling alone. It is 
precipitated, on the addition of strong acetic acid, and also by water in excess, when the 
precipitate is soluble in phosphoric, nitric, hydrochloric, sulphuric, tartaric, and acetic 
acids, also in potash and ammonia. The nitric acid solution is not coagulated by boiling, 
and the potash solution only then coagulated on boiling when nitric acid is added hot. 
A strong solution of acetate of potash acts much as does the above reagent. The solu- 
tion may be boiled without much coagulation, unless acetic acid be added, when flocculi 
form. 
