193 
Notices of Books. 
the table of reactions given, that metaxin is only doubtfully soluble in 
dilute potash, it appears probable that it is really soluble in water. It 
dffers from globulin and albumin in not being soluble in io 0 / o solution 
of common salt, and from albuminates in not being readily soluble 
in dilute acids and alkalies. 
Of the substances which are described as constituting the nucleus, 
linin and paralinin form one group, pyrenin and amphipyrenin form 
another, and chromatin stands by itself. They all agree in being 
digestible by trypsin, and differ in this respect from the plastins, cyto- 
plastin and chloroplastin. 
So closely do linin and paralinin resemble each other, that the 
author is doubtful if he is justified in regarding them as distinct sub- 
stances. The main difference between them is that linin is not 
digested by pepsin, whereas paralinin is. They resemble the glo- 
bulins, especially myosin, in being soluble in 10% solution of 
common salt, but not in stronger solutions, as also in being soluble 
in dilute potash; — but, unlike the globulins, they are insoluble in 
hydrochloric acid, whether dilute or concentrated. 
With regard to pyrenin and amphipyrenin, they differ mainly in 
their solubility in 10% common salt solution, the former being more 
readily soluble than the latter, and in that the former stains whereas 
the latter does not. They dissolve in potash solutions, whether 
dilute or concentrated, and they are not digested by pepsin; they 
are also soluble, but not readily, in i% solution of hydrochloric 
acid. 
Chromatin is apparently soluble in water, but its apparent Solubility 
when a nucleus is treated with water may be due to the alkalinity 
of the protoplasm. It is soluble in saturated solution of magnesium 
sulphate, in solutions of disodium phosphate and of common salt, 
and in potash, but it is not soluble in acetic or hydrochloric acid, 
nor is it digested by pepsin. 
It remains to point out the relation between these substances and 
those which had previously been described as entering into the 
composition of the protoplasm. According to Zacharias *, the nucleus 
consists of three proteids — nuclein, plastin, and albumin ; the chloro- 
plastids and the cytoplasm of two proteids — plastin and albumin. 
Since Zacharias has shown that his ‘ nuclein ’ is localised in the 
1 In Bot. Zeitg. 1882 and 1883. 
