302 
It is obvious that for this it was necessary to examine a number 
of isomeric and stereoisomerie sugars with regard to their behaviour 
towards the kidneys, and then, not only hexoses, but also pentoses. 
Jhr. ALBERDA VAN EKENSTEIN, Prof. Backer, Prof. BörseKeN and Prof. 
NeuBeRG were so kind as to assist me in this as much as possible. 
Hereby | again tender them my cordial thanks. Nevertheless the 
diversity of material was very limited. 
The methods pursued did not differ from the previous ones *). 
They were based upon the reducing powers of the secreted artificial 
urine, and that of the perfusion liquid. This perfusion liquid, in which 
the sugars were dissolved, “again had the following composition : 
NaCl 0.5°/,, KCl 0.02 °/,, CaCl,.6 aq 0.04°/,, NaHCO, 0.285 °/,. 
The determination of the sugar was made, as in the previous case, 
according to Bana (1916). Lately however the newest method of this 
writer was used’). This also is based upon the determination of the 
reduction. Here the diserepaney which can arise from differences in 
the intensity of boiling is eliminated, and that because hot steam is 
passed through the boiling liquid, whereby the cuprous oxide is 
instantly changed into cupric by means of iodic acid Furthermore 
the oxidation by the air is avoided. The final titration is carried out 
with O,OL n thiosulphate and starch solution. If @ ee. thiosulphate 
are used then the reduction in terms of glucose can be calculated 
from the formula (1.97— a): 2.8. [f no reducing substance or sugar 
is present then the answer must be found to be: « = 1.97, which 
is indeed the case if the substances used are pure’). This new 
method, it appeared, like the old one also gave very good results. 
The results are even nice. On the whole the figures obtained for 
the reduction, by the new method, are higher than those obtained 
when the old method is used, but, seeing that the purpose here is 
comparative research it is mostly not of vital importance. 
In order to have an introduction for our procedure the arbitrary 
C-OH 
hypothesis was made that the | group in the glucose molecule 
H-C-OH 
caused the retention. 
1) Compare also HAMBURGER and BRINKMAN, Biochemische Zeitschrift 88, 97, (1918). 
*) Bane, Biochemische Zeitschrift, 92, 344, (1918). 
5) We wish to call special attention to that because after long searching it has 
appeared that the KCI “pro Analyse" of Kantyaum contained reducing substances. 
This was also the case with the KCl which was supplied by the British Drug 
Houses as chemically pure. After repeated crystallization the KCl was freed from 
reducing substances and then we obtained like Bane, a value of 1.97 for a. 
