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Notices of Books . 
chromatin-granules, it appears probable that it is identical with the 
substance which the author terms chromatin. 
The author points out that the substance which Zacharias found 
to constitute the nuclear framework, and termed plastin, differs widely 
in its reactions from both cytoplastin and chloroplastin ; Zacharias’ 
nucleo-plastin is the author s linin. 
The substance in the nucleus which Zacharias terms ‘ albumin ’ 
is apparently the same as the author’s paralinin, assuming, as the 
author contends, that there is no albumin in the nucleoli. 
The substances pyrenin and amphipyrenin, described by the author, 
seem to have no parallel in previous investigations. 
With regard to the chloroplastids, the ‘ plastin ’ and ‘ albumin ’ of 
Zacharias appear to be the equivalents of the author s chloroplastin 
and metaxin. Similarly, in the case of the cytoplasm, Zacharias’ 
‘ plastin ’ is the cytoplastin of the author ; the ‘ albumin ’ is recognised 
by both writers. 
Of the substances described by the author, the majority, namely 
cytoplastin, chloroplastin, pyrenin, amphipyrenin, chromatin, linin, 
are not digested by pepsin ; metaxin and paralinin being the only 
digestible proteids. On this ground the author refers the proteids 
of the former group to the class of nucleins. No one of them seems 
to agree in all its reactions with any form of nuclein as yet described. 
Hence it appears that there is no one substance which is to be re- 
garded as nuclein proper, but that the term must be used for a class 
of proteids agreeing in their indigestibility by pepsin, and differing 
from each other in minor points. 
As to the digestible proteids, metaxin and paralinin, their reactions 
do not identify them with any known group of proteids. Metaxin, 
in fact, does not appear to be allied to any of the groups of proteids, 
but paralinin is clearly allied to the globulins. 
One general conclusion to be drawn from these researches is this, 
that the globulins, albumins, albumoses, etc. which have been obtained 
from plants are not constituent elements of the protoplasm ; they are 
simply reserve-materials. 
Since the investigation was carried out entirely by micro-chemical 
methods, and in view of the great difficulty of such observations, it 
is possible that some of the author’s conclusions, especially those 
regarding the nucleus, may eventually have to be somewhat altered. 
But be this as it may, the author offers us valuable information as to 
