26 
mate, egg-white and gelatin solutions, caffeine, antipyrine etc. 
The precipitates with antipyrine and caffeine solutions, 
with pyridine and quinoline-vapour, and other basic sub- 
stances completely resemble those occurring in living cells: 
little spheres or globules which show Brownian movement 
and gradually aggregate to larger masses, which on the 
addition of water dissolve and behave towards reagents 
as tannin precipitates, all of which completely resembles 
what we observe in living cells. 
From the above experiments it is evident that what 
Loew and Bokorny take to be reactions of active protein 
are in reality none other than reactions of tannin and 
the proteosomes none other than precipitates of different 
basic substances with tannin. It is further evident that 
after: death these precipitates can be as distinctly produced 
as in living cells and can therefore hardly be called vital 
reactions. 
The question what substances the precipitates can 
contain in addition to tannin-compounds is more difficult 
to answer than it was to demonstrate the tannin character 
of the precipitates in living cells. That other substances 
may be present in the precipitates, is already clear from 
observations on cells containing red colouring matter as 
well as tannin in solution in the cell-sap. The precipitates 
take up the red colouring-matter and large red-coloured 
spheres finally arise through the aggregation of many 
globules. 
The question whether the intravital precipitates can 
contain protein will now be dealt with. As already stated 
Pfeffer !) assumes that the precipitate which is produced 
in Spirogyra by ammonium carbonate, consists of protein 
and tannin, which, according to him, both occur in solution 
in the cell-sap. The acids present in the cell-sap are 
M Uc1p%259 
