( 928 ) 
An example taken at random may serve to illustrate this mistake. 
We wish to determine the effect of an addition of some water, for instance, 
on the interchange of the component parts of blood-corpuscles and serum. 
For this purpose we took a certain volume of blood. Let us for the reader’s 
convenience assume that this volume amounted te 100 c.c Let us suppose 
these to contain 40 c.c. of red blood-corpuscles, and 60 ¢.c. of serum From 
these 60 c.c. of serum we take 20 ec, and dilute them with 7}/, cc. of 
water, but now we do not add these 27'/, c.c. of fluid to the rest of the blood, but 
only 20 c.c., so that the volume of the blood becomes 100 e.c. again. Now it 
is obvious that it cannot be expected, as Mr. Gryns does, that the blood treated, 
will contain the same absolute amount of substances as the original blood, since 
serum has been kept back. This Gryns overlooked, and a similar mistake he made 
in the calculation of the experiments, in which the serum was made hyperisolonic 
by the addition op NaCl. 
If Mr. Gryns, avoiding the mistake made by him, repeats the 
ealeulation, he will no longer arrive at the conclusion that “the 
mistakes in our analyses are much greater than the differences upon 
which our conclusions are based”, nor will these calculations afford 
him grounds for opposing our views as to the permeability of 
blood-corpuscles. 
Physiology. — “A tumour in the pulvinar thalami optict. A con- 
tribution to the knowledge of the vision of forms.” By Prof. 
C. WINKLER. 
(Communicated in the meeting of 28 January 1911). 
The case, which supplied the material for this paper was the 
following : 
F. t. B, aged 22, who entered the hospital on February 25th 1909, was born 
from healthy parents and did not suffer from any illness before, neither traumata, 
nor venereal infection. He partook of alcohol and tobacco in a moderate way. 
Since Dec. 1908 there was a stiffuess of the right leg, followed afterwards by 
unsteadiness in the movements of the right hand. The commissure of the lips on 
the right side began to drop. By and by the patient became aware of a pecutiar 
sensation in the right half of the body, a certain numbness, and he commenced 
to stammer. Ali these symptoms gradually grew worse without any aching of head 
or timbs, without dizziness, without disturbances of vision or hearing, as far as 
the patient knows. Only his memory was impaired. 
During March and April notes have been taken about the case. The patient, a 
very intelligent individual, takes an interest in his surroundings and has right 
notions as to space and time; the pulse is feeble, 92 per minute, and regular. 
