455 
In the last term of (17) we may consider (3) to be constant and 
so we have N 
ee Th] LAs 
—x > Bee: 
i Piet Pi 
where 7;; represents the distance of the ¢th body from the j-th. 
We so obtain 
mi; SN? _ Mv; Bera: stre keer Teg 
a tels ) — 2x —-—— — hz Smjr - x’ = — 
gd li i Pi i ERA AN 
> 5 5 
Putting 
ing ae ee 
we have 
EARN Ne EEN 
ds =| 1 —22>—+42| 3 gent Shir Aerdt 
ie - aye i hij Pi 
et ei ES) 
Ee, hy 
1 t 2 2 2 
+82 (wide yjdy + 2,dz)dt Us cy Se (de +dy?+dz*) © 
iN j jl) / 
where j in the last term of y,, does not take the value /. 
This is the field required. 
Physiology. — ‘Researches on the function of the sinus venosus 
of the frogs heart’. By B. Brouwer. (Communicated by 
Prof. HAMBURGER). 
(Communicated in the meeting of May 27, 1916). 
I. Lifect of CaCl,, KCl, NaCl and osmotic pressure. 
Introduction. 
As we know the myogenous theory of the heart supposes the 
impulse to the automatic motion of the heart to originate in the 
muscular substance of the sinus venosus. There must be a centre 
there whence the rhytmic stimulus takes its origin, which 
stimulus is transmitted through auricle and ventricle. From a chemi- 
‘al point of view tbere is no longer anything mysterious about the 
occurrence of such periodical stimuli, since Brenig has made us 
acquainted with the periodical contact-catalysis. 
The reader will remember his experiment: a mercury-surface is 
covered with a solution of hydrogenperoxyde. A red layer of HgO 
is formed, but after a short time it disappears and Q, being set free, 
a pure mercury-surface is the result. This phenomenon is repeated 
rhythmically. 
Now it must be esteemed of the greatest importance to get 
acquainted with the chemism of the stimulus originating in the 
sinus venosus. 
