462 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. VI. 
that what remains in the central body as well as in the peripheral zone 
is formed of plastin only. 
These facts show quite clearly that artificial gastric juice does dissolve 
a portion of each part of the cell in the Cyanophycee. That which is 
left in the peripheral zone is largely, if not wholly, composed of plastin 
while a part of what is left in the central body appears to have the 
character of a nuclein compound. The concentrated character of the 
substance left in the central body and its coarsely reticular appearance 
can only be explained on the postulate that the reagent has removed 
material from the central body. What contributed to the view of Fischer 
that the digestive fluid exercises only a contracting, not a dissolving 
action, was the assumption that nothing appeared to be removed from 
the cell acted on by the digestive fluid. There is one feature in all 
digestive experiments on the Cyanophycee which ought to be borne in 
mind. The membranes in the Cyanophycee have a colloid character 
and as such they do not readily permit the diffusion through them of 
colloids in solution. Pepsin is much more a colloid than a crystalloid 
and consequently it will not penetrate the membranes in the Cyano- 
phycee with the same facility as hydrochloric acid and, therefore, a 
slighter effect is produced at the end of twenty-four hours than is 
obtained when naked cytoplasmic masses, like the cells in higher 
organisms, are treated with gastric juice. This would account in part 
for the results obtained by Fischer. 
There can be, therefore, very little doubt that a chromatin-like sub- 
stance is present in the central body of cell of Cyanophycez. It is much 
less in amount than the chromatin of the smallest nucleus in a highly 
organized cell, and it does not appear to vary in amount in the various 
celis of a trichome nor in those of a preparation of filaments. In other 
words, this chromatin-like substance appears to be fixed and unchanging 
in amount in whatever condition the cells may be. This chromatin-like 
substance never appears to enter any condition resembling, in the 
remotest degree, that of mitosis and whenever the cell divides this sub- 
stance is distributed as it is in the resting cell,that is, uniformly through- 
out the central body. It is impossible, then, to regard the central body, 
with Biitschli, as the homologue ofa nucleus. From its structure and its 
chemical character it is rather to be regarded, as Fischer claims, as a 
more active portion of the cytoplasm. 
When trichomes of Oscillarie. Tolypothrix, ' Scytonema, Mucrocoleus 
terrestris, are digested for twenty-four or forty-eight hours with artificial 
gastric juice and then stained for twenty-four hours with picrocarmine, 
what remains of the central body is coloured red and at times the peri- 
