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630 OPUAXS OF GENERATION.
sosaccharic acid. It is difficult to state whether this glucosamine was
derived from the vitellin or from some other constituent of the yolk.
The principal points in the preparation of ovovitellin are as follows:
The yolk is thoroughly agitated with ether; the residue is dissolved in
a 10-per cent common-salt solution, filtered, and the vitellin precipitated
by adding an abundance of water. The vitellin is now purified by repeat-
edly redissolving in dilute common-salt solutions and precipitating with
water.
Ichthulin, which occurs in the eggs of the carp and other fishes is, accord-
ing to Kossel and Walter, an amorphous modification of the crystalline body
tchthidin, which occurs in the eggs of the carp. Ichthulin is precipitated on
diluting with water. It was formerly considered as a vitellin. According to
Walter it yields a pseudonuclein on peptic digestion; and this pseudonuclein
gives a reducing carbohvdate on boiling with sulphuric acid. Ichthulin has the
following composition; C 53.42, H 7.63, N 15.63, 22.19, S 0.41, P 0.43 percent.
It also contains iron. The ichthulin investigated from codfish eggs by Levene
had the composition C 52.44, H 7.45, N 15.96, S 0.92, P 0.65, Fe+O 22.58
per cent, and yielded no reducing substances on boiling with acids. The pure
vitellin isolated by Hammarsten from perch eggs had a similar behavior and
was very readily changed by a little hydrochloric acid so that it was converted
into a typical pseudonuclein. The codfish ichthulin yielded a pseudonucleic acid
with 10.34 per cent phosphorus, but this acid still gave the protein reactions.
McClenden 1
has prepared a vitellin from frogs’ eggs which he calls batrachiolin.
The yolk also contains albumin, besides vitellin and the above-men-
tioned proteins.
The fat of the yolk of the eg?, Liebermann 2
claims, is a mixture of
a solid and a liquid fat. The solid fat consists principally of tripalmitin
with some tristearin. On the saponification of the egg-oil Liebermann
obtained 40 per cent oleic acid, -38.04 per cent palmitic acid, and 15.21
per cent stearic acid. The fat of the yolk of the egg contains less carbon
than other fats, which may depend upon the presence of monoglycerides
and diglycerides, or upon a quantity of fatty acid deficient in carbon
(Liebermann). The composition of yolk fat is dependent upon the
food, as Henriques and Hansen 3
have shown that the fat of the food
passes into the egg.
The phosphatides of the yolk seem to be of various kinds. Thier-
felder and Stern have found three different phosphatides. One of
these, which was soluble in alcohol-ether, behaved like lecithin. The
second was soluble with difficulty in alcohol, but readily soluble in ether,
contained 1.37 per cent N and 3.96 per cent P. The third was a diamino
1
Walter, Zeitsfhr. f. physiol. Chem., 15; Levene, ibid., 32; Hammarsten, Skand.
Arch. f. Physiol., 17; McClenden, Amer. Journ. of Physiol. 25; see also Plimmer
and Scott, Journ. Chem. Soc, 1)3.
2
PfluKer’s Arch., 4:5.
•Skand. Arch. f. Physiol., 14.
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