24 
It agglutinated more or less and a portion had clearly 
become much less soluble in water, so that after some 
days in an excess of water there was still a considerable 
resinous residue undissolved. It is possible that Loew 
and Bokorny succeeded by heating and by the action of 
nitric acid to transform part of the precipitate in the cells 
into an insoluble modification, but this is by no means a 
proof of its protein nature. 
Loew and Bokorny !) declare the formation of proto- 
somes with ammonium carbonate, antipyrine and caffeine 
to be a true vital reaction. They say that when the cells 
are dead, formation of protosomes can no longer take place, 
because the active protein has become passive. I shall 
proceed to show how, starting from dead material, preci- 
pitates can be produced with antipyrine, caffeine and other 
basic substances, which completely agree with those observed 
in living material. 
That in dead cells of Spirogyra no precipitates occur 
with the above basic substances, is simply due to the fact 
that the dead protoplast and the cell-wall allow the tannin 
to escape. À portion of the tannin gets outside the cell 
and another portion enters into combination with the 
protein-substances present in the cell. It is specially fixed 
in the nuclei and the pyrenoids. Now antipyrine, caffeine 
and other basic substances can obviously no longer cause 
any precipitate in the vacuole. 
It can be proved as follows that in dead Spirogyra part 
of the tannin passes out. Pieces of Spirogyra-filaments are 
placed between slide and cover-slip in a 1°/, solution of 
egg-white or in a !/, ‘/, gelatin or glue solution. These 
colloids do not penetrate into the cells and cannot therefore 
form any precipitate with the tannin of the cell-sap. When 
) ©. Loew and Th. Bokorny, Ueber das Verhalten von Pflanzen- 
zellen zu stark verdiünnter alkalischer Silberlôsung. Bot. Centralbl. Bd. 
XXXVIIT. p. 614. 
