THE STRUCTURE OF PROTOPLASM 
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chemical equivalent for many descriptions of the breaking up of the chro- 
mosomes in the telophases and their reconstitution in the prophases as 
found in current cytological literature. 
The concrete data of the chemistry of the colloidal state so far relate 
chiefly to simple two-phase systems, and the conditions of the two phases 
are conceived as a more and a less watery phase of a single compound, 
though there is nothing in the conception of a sol to suggest such a limi- 
tation. Little has been done, too, toward the analysis of those intermediate 
conditions between the sol and the gel, though it is perhaps just here that 
the bulk of cytological phenomena belong. Still, there are those who on 
the meager data already available have formulated theories of protoplasmic 
structure in terms of colloidal systems. 
To present a picture of the p resent chemical theories of protoplasm we 
must recognize two quite divergent tendencies or schools of thought which 
are largely represented amongst biologists and chemists of the day. First, 
the group of which we may take Verworn as a representative, who hold 
that a single very complex chemical compound, for Verworn the biogen, 
built up on the benzol ring and v/ith Ehrlich side chains for dissociation 
and restitution, is the essential physical basis of life. The other visible 
constituents of the cell are to be regarded as more or less accessory. Life is 
the dissociation and restitution of biogens ; all else is secondary. 
The second school, which we may represent by Hofmeister, holds that 
the protoplasm is essentially an aggregate of compounds of varying com- 
plexity. Hofmeister takes at once the conception of a polyphase colloidal 
system as the basis of his account of cell organization. 
The theory of a single living substance passes easily into the conception 
of specific chemical substances for each species of organism as developed by 
Kossel and carried still further by Correns in his theory of self- and cross- 
sterility and -fertility as due to similarity and dissimilarity of the specific 
individual substances in the same or different individuals. Correns has 
developed the interesting criticism of the doctrine of individual stuffs 
that even if the possible number of stereoasome/s of a carbohydrate with 
40 carbon atoms in its molecule was as great as 2^°, about a billion stereoi- 
somers, there still would not be enough to provide a different one for each 
rye plant, for example, since a single crop of rye in Europe amounts to 41 
billion individual rye plants. Reichert would have the genus, species, 
variety, race, sex, individual, and even tissue or organ stuffs the countless 
stereoisomers which the complexity of the protein molecule makes possible. 
The theories which postulate a single living substance have been de- 
veloped by many into a doctrine of protoplasmic structure as a simple, 
even a two-phased system. Biitschli's foam or alveolar theory would find 
the essential substance in the continuous phase while the contents of the 
alveolae, the disperse phase, is simply a watery cell sap. Various granular 
inclusions in the continuous phase are also assumed. Beijerinck and 
