1164 
The excitation of fresh contractions of a heart, fed with a totally 
inactive circulating fluid (potassium-free RINGER's mixture) or with 
a fluid containing correctly proportioned antagonistic quanta of pot- 
assium and uranium is, therefore, to be ascribed to a broad bundle 
of beta-rays of very low penetrating power. That this non-homo- 
geneous mass of weak rays should be absorbed in the air according 
to an almost exponential law is not in the least surprising. Nor is it 
to be wondered at that subsequently what comes through the air 
from various distances is completely absorbed in the organ. The 
foregoing experiments also show that the quanta of uranium, 
which at the several distances counteract the restoring influence of 
the radiation so that the heart’s contractions excited by the meso- 
thorium cease again, are subject to the same quantitative law the 
absorption of the radiation has to obey. As the distance increases 
these uranium quanta should be diminished in such a sense that their 
logarithm remains inversely proportional to the distance. 
The qualitative relation induces me to assume that the biologically 
active quantum of energy shot out from the mesothorium in its weak 
beta-radiation, and the uranium dosage, required for the equilibrium, 
and arresting the contractility of the heart, are antagonistic. The 
radiation as well as the radio-active substance sent into the heart 
are to derive their activity from the mutually compensating energies 
carried along with them. 
The character of the weak beta-rays, in which lies the whole gist 
of the matter, seems to be rather well defined by the above, at 
least when, as is the case in our experiments, the restoring influence 
is considered. An obliterating influence is effected also by the more 
penetrating rays and perhaps it may be for the very reason that we 
cannot get rid of them, that the recovery, obtained through artificial 
radiation, was always transitory, never persistent. 
The following equilibria are obtained when working with a radium- 
preparation of 3 mgrms in the same way as has been described 
above for the mesothorium-radiation. This preparation yields the 
advantage of a more even area of radiation. (See table p. 1165). 
We will also graphically represent these data by plotting the 
distance along the axis of the abscissae to the logarithms of the 
uranium doses as ordinates. 
This gives a curve represented by the dotted line which again 
may be considered as approximately straight. 
It is obvious that by extrapolating mentally towards the ordinate 
take into account the secondary rays of very low penetrating power that are 
generated in passing through the screen. 
