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adrenalin-cholin is biologically reciprocal. The sensibilization through 
adrenalin and cholin with its peculiar properties in respect of both 
kinds of corpuscular radiators has thus far been observed, besides 
for the heart, also for the synapsis between vasomotors and vascular 
muscle-wall. Another part of the substances, which in oligo-dynamic 
addition can bring about a sensibilization of some duration, have 
the character of cytolisins: (in a higher concentration they cause 
hemolysis). Most often cytolysis is attributed to dilution of the boun- 
dary-layer. When we endorse this hypothesis, also this form of 
sensibilization is acknowledged as a form of superficial effect (24). 
Frenstra has demonstrated that for some of the radio-active elements, 
which can replace potassium, the proportion relative to Na and Ca 
which is required to satisfy the balancing-equilibrium, can be cal- 
culated. This proportion appears to fall within the concentration- 
latitude, in which the replacement may be applied. For other sub- 
stitutes calculation is impossible as they are colloidal in the modified 
Ringer-solution. In this case, however, there can be no question 
about interior action: their activity can be interpreted only by 
adsorption to the cell-surface. So long as they are in suspension in 
the circulating fluid they can evidently not exert any raying-effect 
worth mentioning. 
Beneath the cell-surface, to which we suppose the radio-active 
elements to be attached as metal-points in fixed protein-composition, 
or to be adsorbed in colloidal or atomic composition, the electric 
phenomena are at work. This appears from the fact that the 
electrocardiogram of a uranium-, thorium-, or ionium-heart, is not 
distinguishable from that of a potassium-, resp. rubidium-heart. 
Anyhow not in the beginning. Also the electrocardiogram of a 
heart, which pulsates with S. Rineur’s solution without calcium, 
and whose cells must therefore be imagined devoid of calcium 
metal-points, remains unchanged in the beginning. Since the hypo- 
thetical lipoid-layer can never be continuous, and therefore can never 
represent a perfect dielectricum, the old theory of ENGELMANN is still 
intact, according to which the transmission of the stimulation into 
the mass of the heart-musele is brought about by the transmission 
of the current from cell to cell. 
In this paper there is no opportunity for a further exposition of 
the surface-hypothesis for other cases than those round the heart 
muscle-cells. It cannot be expected that all cell-surfaces have their 
own electric charges, nor need the hypothetical catalysators occur 
on all contact-planes. 
