162 
The real values can then be about 6°/, sma//er than those calculated 
in table IV. The calculated values are of the expected order of 
magnitude, and change little with the temperature. 
TABLE IV. 
Fr | D | Sige in’) 10° 
0 0.226 1797 4.2 
23.2 0.524 935 3.8 
32.9 | 0.649 | 755 3 9 
43.4 0.84! 618 3.8 
52.3 0.987 531 3.9 
62.0 1.168 | 459 3.9 
70.2 | 1.352 | 406 3.9 | 
In the calculation of the radius use has been made of the deter- 
minations of the internal friction of Bingham and Warre *) and of 
the N-value of MILLIKAN *). 
In a following paper we shall communicate the results of a series 
of experiments, which enable us to determine the value of the 
radius by another way. 
The diffusion experiments will be continued with other substances. 
Physiology. — “The movements of the heart and the pulmonary 
respiration with spiders’ *). By Dr. V. Witiem (Ghent). (Com- 
municated by Prof. van RIJNBERK). 
(Communicated in the meeting of May 27, 1916). 
We do not know anything about the respiratory movements witb 
spiders. The only modern investigator who has tried to find them 
experimentally, was F. Prareav, he applied in vain to Arachnida 
the artificial methods that had succeeded with insects; not a single. 
method of investigation made him find the slightest change of the 
shape of the body that could be attributed to inhalation or exha- 
1) BINGHAM and Ware. Zeitschr. f. physik. Chemie. 80. 684 (1912). 
2) 1. C. 
3) According to investigations made in the Physiological Laboratory of the 
University of Amsterdam. 
