(m ) 
These experiments prove: 
a. The osmotic pressure of the blood serum sometimes remains 
the same after loss of blood, but generally sinks a little. 
The.percentage of albumen is diminished (as is seen from exp. 
I with the small loss of blood and from the change in resistance in 
exp. IV and II). 
c. The resistance is diminished by bleeding. 
d. The ash percentage of the serum increases; since the osmotic 
pressure remains unchanged or sinks, this means that ; 
e. the urea percentage of the blood serum decreases after loss of 
blood, but does not sink below 1.967 °/ 0 when the albumen had been 
precipitated by means of asaprol, or below 1.64% when Hofmeister’s 
method had been applied. 
Moreover I dould state that the blood of animals that had suffered 
a severe loss of blood, (exp. IV and II) coagulated much more 
quickly than normally. This phenomenon has also been stated with 
mammals after bleeding % 
I think we are justified to conclude that after loss of blood the 
serum of sharks is diluted by a liquid which is richer in salt and 
less rich in urea. Perhaps this liquid is salt water from the sea, 
perhaps lymph which is in its turn supplemented by sea water; but 
at all events, even after the severest loss of blood a rather high 
percentage of urea remained in the serum. It seems that this serum 
is supplied by the liver. In exp. IV. after bleeding the liver was 
extirpated and the urea percentage determined. I found it to be 
1.16%, while Schroeder gives 1.36%- 
Physiology. — “On the constitution of the urine of sharks with 
normal and increased diuresis.” Bij Mr. F. J. J. Buijtendijk- 
(Communicated by Prof. H. Zwaardemaker). 
(Communicated in the meeting of September 25, 1909). 
The urine of sharks, as is the case with most cold-blooded animals, 
has a lower osmotic pressure than the blood serum. Also in man, 
the urine is under certain conditions more diluted than the serum, 
in some cases of human polyuria, namely, the blood was found to 
be of normal concentration (A = — 0.56°), the urine on the ot ei 
hand to be very much diluted (A = — 0.22° to — 0.17° C.). Metznbb ) 
x ) Von den Velden, Arch. f. exper. Path. u. Pharm. 1909. 
Metzner, Nagels Handbuch der Physiol. II, Bd. le H 
