matter of fact, they are allowed to pass through. On the other hand 
however, in accordance with the hypothesis, d-galactose, l-xylose 
and d-ribose are retained, but this happens only with a part of each 
of the sugars which are passed through. As regards the sugars 
which, from the hypothesis, were expected to pass through completely, 
they all indeed passed through the glomerular membrane except the 
d-xylose, which was partially retained. To this partial retention we 
shall return again, as has already been said, in the next article. 
If we accept for the time being that even where a total retention 
had to take place, a partial one satisfies the hypothesis, then in any 
case there still remain the l-mannose and the l-arabinose of which, 
in contradiction to the hypothesis, nothing is retained. There will 
therefore be an inclination to hold a larger group of atoms of 
the glucose molecule responsible for the retention, for instance 
C—OH 
H— C—OH. But also in this case l-arabinose had to be retained 
| 
OH—C—H 
completely. 
C— OH 
| 
H-—C—OH 
If the group of atoms is taken still larger viz. OH—-C—-H 
H aide OH 
then this could be held responsible for the retention of glucose, but 
then the difficulties of the partial retention still remain. For the 
present therefore it is risky to explain the retention by means of 
the image of the loek and key, unless, instead of a part of the 
molecule, the grouping of the whole is taken. Dr GRAAFF ') came 
to a more or less like conclusion through his detailed experiments 
in connection with the behaviour of typhoid and para typhoid bacilli. 
towards stereoisomeric sugars. 
As matters stood now there would be the inclination to get a point 
of contact with the specific physical properties of glucose, and we 
thought of surface tension, viscosity and adsorption. 
As regards the surface tension, comparative experiments were 
made with d-glucose and d-fructose *); of the latter sugar it will be 
1) W.G pe Graarr: The biochemical characters of paratyphoid bacilli. Leiden, 
S. C. van Dogspuren, 1918. 
4) We take these especially because, as a rule we have sufficient quantities of 
them at our disposal. 
