( 704 ) 
nution of the tannin content during the formation of transverse walls, 
point to the tannin being necessary for, and used up in the formation 
of transverse walls. 
In order to obtain still greater certainty with regard to this con¬ 
clusion, the influence of antipyrine and caffeine on the formation of 
transverse walls in Cladophora was investigated. With ferric chloride, 
osmic acid, and antipyrine I did not obtain tannin reactions in Cla¬ 
dophora and I therefore was interested in knowing how, for instance, 
the formation of transverse walls would be affected by transferring 
to a one percent antipyrine solution. 1 found that transverse walls, 
which were just beginning to be formed, continued to grow until 
they* were completed. This was even the case if the specimens were 
left in antipyrine solution during the whole of the process of cell 
division. This result still further strengthens my view that in Spirogyrd 
the interruption or prevention of transverse wall formation is wholly 
due to the fixation of the tannin. For in Cladophora, where no 
tannin can be used in the formation of transverse walls, a one percent 
solution of antipyrine does not bring about this disturbance. The 
only ready explanation which, in my opinion, can be given of the 
results obtained in the conjugation and transverse wall formation, is 
this, that the tannin serves as plastic material in the building up of 
the cell wall. 
I wish to add a few results to those already mentioned, which 
point to a connexion between the tannin content and growth of cell 
wall. In Spirogyra filaments cells are sometimes observed, which, j 
judging from Ihe position of the transverse walls, are distinguished 
from the others by increased turgor. These cells are generally also 
distinguished by a larger starch content. On closer examination it 
is found that the growth of these cells is less than that of the others, 
or that growth has completely come to a standstill. These symptoms 
indicate a pathological condition, for generally I was able to ascertain 
that the above-mentioned cells did not divide further and died off. 
I cannot give the reason for this condition, but it is remarkable that 
the tannin content of these cells as revealed by antipyrine or caffeine 
so ution, is larger, and often much larger, than that of the other 
cells. Once more it is found, as in the case of cells in which conju¬ 
gation failed that a cessation of growth is accompanied by an 
increase in the tannin content. 
As was shown by the investigations of Gerassimoff ') and fl 
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