371 
the fact that both the modifications in which a large number of 
sugars occur, need not behave in the same manner towards tliose 
organisms. Besides that, the circumstances in such experiments are 
somewhat different from those in our cases; for have we not to do 
with a disturbance of equilibrium in the ferment experiments, which 
disturbance is the result of the eventually being used up of one of 
the modifications, but is adjusted again? (cf. p. 367). 
The behaviour of the kidneys towards sugars other than 
galactose and xylose. 
It has appeared that from the experiments described up to this 
three cases can be distinguished : 
1st. The sugar, if its concentration does not exceed the plhysiolo- 
‘gical border for more than to a very slight extent’), is compdetely 
retamed. This applies exclusively to glucose. ‘ 
2nd. A partial retention takes place; This was the case with 
solutions of d-galactose, of d- and l-xylose, of d-ribose and of maltose. 
3°, Nothing is retained. This we found for |-glueose, l- and 
d-arabinose, l- and d-mannose and lactose. 
But all sugars mentioned under 1, 2 and 3 exhibit multirotation . 
and occur therefore in 2 moditications. The question is thus obvious: 
why do those sugars mentioned under 1 and 2 not behave like 
galactose, i.o.w. why do they not all exhibit partial retention? I 
think that the explanation must be sought herein, that, of the glucose 
both modifications are retained, of the galactose and other sugars 
mentioned under 2 only one modification, and of arabinose and the 
others mentioned under 3 neither of the two forms. 
We will set ourselves the task to test this conjecture by experiment. 
We are engaged upon this; we have already obtained satisfactory 
results. 
Summary and conclusion. 
The experiments described above are concerned with the question 
what the cause can be that of a0.1 °/, solution of d-galactose 
only a part of the sugar is retained and the other not. Two explana- 
tions were possible. The first was that the original galactose-solution 
which we used was of too strong a concentration viz. 0.1 °/,. We 
thought namely of our earlier researches in connection with glucose, 
where it appeared amongst other things that when there is passed 
1) Hampurger and Brinkman, Die Toleranz der Nieren fiir Glukose, Bioch. Zeitschr. 
94, 131, 1919. 
