1335 
with caffeine and antipyrine had been treated according to Boxorny’s') 
11 1/ 0/ 
method with */,, °/, 
ammonia and had thus become insoluble. 
Nor have I been able to obtain a protein reaction when the 
precipitates were some weeks old and had become insoluble. Spirogyra 
can, it should be noted, remain alive for several weeks in a 1 °/, 
antipyrine-solution and in a 0.1 °/, caffeine-solution. At first the 
precipitates aggregate and form globules; gradually their solubility 
diminishes. When the filaments are then transferred into water, the 
globules leave vesicles behind, which have disappeared after some 
days. After a few weeks the globules seem altogether insoluble. In 
dead cells brown globules are found, which are also insoluble in 
water. Neither the globules nor their insoluble residues gave even 
a protein reaction with sugar and sulphuric acid, whilst the proto- 
plast became distinctly colonred red. On the other hand the globules 
gave tannin reactions. 
It is remarkable that Lorw and Bokorny*), who have repeatedly 
insisted on the protein nature of the precipitates, assert in one of 
their latest publications that the colour-reactions for protein sub- 
stances, such as that of Minion and the biuret reaction, are not the 
most important protein tests, although they formerly relied on these. 
Now they prefer coagulation by rise of temperature, by alcohol 
and by acids. 
I treated Spirogyra-filaments, with precipitates produced by 1°/, 
solution of caffeine, by Bokorny’s method with a saturated caffeine 
solution containing 20°/, alcohol or I exposed the filaments for a 
short time to the action of 10°’, nitric acid or warmed them to 
60° in a 1°/, solution of caffeine. In the first two cases I observed 
solution, in the last case coalescence. The results by no means proved 
the protein nature, as is especially evident from the following 
experiments. 
When I mixed 1°/, solutions of gallnut- or of Spirogyra-tannin 
with an equal quantity of a L°/, caffeine-solution and heated tlie 
mixture to 60° or added 10°/, nitric acid, the precipitate which 
was formed underwent a modification. 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 con- 
siderable resinous residue undissolved. It is possible that Lorw and 
Boxorny succeeded by heating and by the action of nitric acid to 
transform part of the precipitate in the cells into an insoluble modi- 
fication, but this is by no means a proof of its protein nature. 
1) TH. Boxorny, Zur Kenntnis des Cytoplasmas. l.c. p. 106. 
2) O. Loew und Tr. Boxorny. Aktives Eiweiss und Tannin in Pflanzenzellen. l.c 
87% 
