Physiology. — “On Polonium Radiation and Recovery of Function.” 
By Prof. H. ZWAARDEMAKER. 
(Communicated in the meeting of October 25, 1919). 
Several organs discontinue their functions, when we remove from 
their environment the potassium-ions, which are always present in 
the circulating fluids. These functions are restored directly when 
potassium is replaced by other radio-active atoms in the circulating 
fluids to a quantity aequi-radioactive to the removed potassium‘). 
It does not matter whether the substitute is an a-rayer or a 
B-rayer, provided its amount be such that the total radio-activity of 
the new constituent is about equal to that of the original one. No 
organ serves our purpose in this experimentation better than the 
heart of a cold-blooded animal, namely of the frog, because the 
blood flows on all sides round its cells, which are separated from 
it only by an endothelium. 
There is a rather large number of elements that can replace 
potassium. Besides rubidium, which was known as such toS. Rincer, 
my co-workers and [ found uranium, thorium, radium, ionium, 
emanation and actinium (as an admixture to lanthanium and cerium) 
to be fit substitutes, while of non-radioactive elements only caesium 
proved serviceable. 
However, it is not only the addition of radio-active elements along 
the blood that can restore the lost function; tbis can also be effected 
by radiation from the outside’). We succeeded in obtaining this 
result with mesothorium contained in glass, with radium screened 
by mica, and unscreened polonium (galvanoplastic on copper). The 
quantity is of equal order with that which inhibits from the same 
distance the cultures of bacteria in their growth. 1} mgr.-hour served 
for radiation that restored the function; 12 mgr.-hour for excitation 
of sterility of bacteria. 
The recovery of function is, therefore, brought about by radio- 
activity, anyhow it is in the case of free radiations. 
1) Verslag Vol. 25, p. 517 and p. 1096, p. 1282. Vol. 26, p. 555 and 
p- 776. Proceedings Vol. 19, p. 633 and p. 1043, p. 1161. Vol. 20, p. 768 and p. 778. 
*) H. ZWAARDEMAKER, C. E. BENJAMINS and T. P. Feenstra, Radiumbestraling 
en hartswerking. Ned. Tijdschr. v. Geneesk. 1916 II, p. 1923 (10 Nov. 1916). 
H. ZWAARDEMAKER and G. Grins, Arch. néerland. de physiol., t. 2, p. 500, 1918 
