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610 BRAIN AND NERVES.
baryta-water. Following a method essentially the same, but differing
slightly, Geoghegan prepared, from the brain, a cerebrin with the
same properties as Muller’s, but containing less nitrogen. Accord-
ing to Parous 1
the cerebrin isolated by Geoghegan, as well as by
Muller, consists of a mixture of three bodies, " cerebrin," " homo-
cerebrin," and " encephalin." Kossel and Freytag isolated two
cerebrosides from protagon which were identical with the cerebrin and
homocerebrin of Parous. According to these investigators, the two
bodies phrenosin and kerasin, as described by Thudichum, seem to be
identical with cerebrin and homocerebrin.
Cerebrin, according to Parous, has the following composition: C
69.08, H 11.47, N 2.13, 17.32 per cent, which corresponds with the
analyses made by Kossel and Freytag. No formula has been given to
this body. In the dry state it forms a pure white, odorless, and tasteless
powder. On heating it melts, decomposes gradually, smells like burned
fat, and burns with a luminous flame. Melting-point is 170-176° C. It
is insoluble in water, dilute alkalies, or baryta-water; also in cold alcohol
and in cold or hot ether. On the contrary, it is soluble in boiling alcohol
and separates as a flaky precipitate on cooling, and this is found to con-
sist of a mass of globules or grains on microscopical examination. Cere-
brin forms a compound with baryta, which is insoluble in water and is
decomposed by the action of carbon dioxide. The variety of sugar
split off on boiling with mineral acids—the so-called brain-sugar—is,
as Thierfelder 2
first showed, galactose. On cleavage with nitric acid
fatty acids (stearic acid) were obtained.
Kerasin (Thudichum), or homocerebrin (Parous), has the following
composition: C 70.06, H 11.60, N 2.23, and O 16.11 per cent. Enceph-
alin has the composition C 68.40, H 11.60, N 3.09, and O 16.91 per cent.
Both bodies remain in the mother-liquor after the impure cerebrin has
precipitated from the warm alcohol. These bodies have the tendency
of separating as gelatinous masses. Kerasin is similar to cerebrin, but
dissolves more easily in warm alcohol and also in warm ether. It may
be obtained as extremely fine needles. Encephalin is, Parous thinks,
a transformation product of cerebrin. In the perfectly pure state it
crystallizes in small lamellae. It swells in warm water into a pasty mass.
As the purity and the chemical individuality of the above-mentioned bodies
is questionable, it is perhaps sufficient in regard to their preparation to simply
call attention to the cited works of Muller, Geoghegan, Kossel and Freytag.
All these methods split with barium hydroxide and purify the cerebroside by
solution in hot alcohol and a precipitation by cooling.
1
Geoghegan, Zeitschr. f. physiol. Chem., 3; Parcus, Ueber einige neue Gehrinstoffe,
Inaug.-Diss. Leipzig, 1881.
1
Zeitschr. f. physiol. Chem., 14.
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