1088 
the split R-top appears, as likewise with the extra-systoles of 
mammals. 
The latter experiments indicate likewise, how, also with other 
methods, the splitting of the R-branch can be brought about. For 
the genesis of the electrocardiagram this fact is of great significance. 
There is, in my opinion, likewise great probability that the purely 
diphasical electrogram of the ventricle consists of a quick diphasical 
R-oscillation, and a T-branch that is either positive or negative. This 
conception would then at the same time afford an explanation of the 
formation of the S-branch. 
Zoology. — “The physiology of the air-bladder of fishes”. By 
Dr. K. Kurerr Jr. of the Physiological Laboratory at Amsterdam. 
(Communicated by Prof. Max Weerg). 
(Communicated in the meeting of November 28, 1914). 
I. The air-bladder as a hydrostatic organ. 
For a long time it has been held that fishes possessing an air- 
bladder could modify its contents by muscular action, which would 
enable them to regulate, within certain limits their own specifie gravity. 
If the fish wanted to go down to lower strata a decrease in the 
contents of its air-bladder would enable it to increase its specific 
gravity. To rise to the surface it needed only to relax the tension 
of the muscles of the air-bladder; the gases in the air-bladder 
expanded and this increased volume carried the fish upward. 
In the latter half of the 19 century, this view, which was 
established more especially by Borgiii, and which prevailed during 
some centuries without being sufficiently tested by experiment, was 
declared erroneous by A. Morrav. Some simple but ingenious experi- 
ments convinced him that a modification in the S.G. by an active 
muscular action was out of the question. 
A fish which, placed in a cage of thin wire, is submitted to 
modifications in the pressure on the water in which it is, behaves 
exactly like the cartesian diver. 
He caused a fish to swim round in a glass vessel which was 
closed hermetically, and which was entirely filled with water. The 
stopper was pierced by a bent glass tube in which the water-meniscus, 
when the fish was at the bottom, was found at a certain point, A 
for instance. When the fish swam upward, the meniscus moved 
slowly forward, that is to say a decrease of the water column 
