1333 
10°/, solution of potassium nitrate and subsequently allowed basic 
substances to act, he found only proteosomes in the contracted vacuole 
and explains this by assuming that on the death of the protoplasm 
the active protein is changed into passive and that then no more 
proteosomes can be formed, so that a vital reaction is given no 
longer. 
Without considering this explanation for the present, I content 
myself with pointing out that, when the above experiments are 
repeated, careful: observation already shows that so far as the 
localisation of tHe precipitate is concerned, Bokorny’s view, accepted 
by KreMM, is incorrect. 
When first abnormal phasmolysis is produced with a 10°/, solu- 
tion of potassium nitrate and this is followed by application of a 
10°/, solution of potassium nitrate which contains in addition 1°/, 
antipyrine or 0.1°/, caffeine or if a rod with ammonia is then held 
above the preparation, precipitation takes place exclusively in the 
contracted vacuole. If the reagents are allowed to act simultaneously 
or in reverse order, ie. if the precipitation is first produced by the 
antipyrine or caffeine solution and is followed by abnormal plasmo- 
lysis, then it is seen that the contraction of the vacuole is accom- 
panied by continued expulsion of the precipitate which is surround- 
ed by cytoplasm. If the whole process is not followed under the 
microscope, but if the tinal result alone is observed, then it is easy 
to imagine that precipitation has also taken place in the cytoplasm 
and thus to draw an erroneous conclusion, as did BokKorny. 
As already mentioned, some investigators have obtained all possi- 
ble protein reactions with the intravital precipitates, whilst others 
have only got negative results. 1 may remark that protein reactions 
at our disposal are in general not sensitive as microchemical reactions. 
When these reactions, namely, the test with sugar and sulphurie acid, 
the biuret test, MirroN’s test and the nitric acid test, are tried on 
minute pieces of coagulated egg-white, the various colorations can 
indeed be easily seen, but.yet it is noticed that most of the reac- 
tions can have no great value for microscopic investigation. With 
MILLoN’s reaction, and the nitric acid and biuret tests the colour 
with very thin pieces of egg-white is very faint. 
With a minute object such as the protoplast of Spirogyra which 
in addition to protein contains also other substances, little is to be 
expected from the three last-mentioned reactions. In accordance with 
this I did not obtain favourable results, but the reaction with sugar 
and sulphuric acid yielded better ones. The objects were left in a 
sngar solution for some time and then sulfuric acid was allowed to 
87 
Proceedings Royal Acid. Amsterdam. Vol. XV. 
