929 
pressure of only 12 m.m. mercury (Fig. 1d). Now again 0.1 adre- 
nalin plus human serum was given, and again a considerable rise of 
the bloodpressure revealed itself (Fig. le). Then we tried 0,05 mer. 
of adrenalin plus serum; also this still produced a marked rise of 
the bloodpressure (Fig. 17) and at last it appeared that 0.01 mgr. of 
0.05 Adr in 0.01 Adr in 0.1 Adr in 0.1 Adr + serum 
human serum human serum NaCl Cat fresh. 
Fig. 1 (f,g,/). Decapitated cat, bloodpressure, abnormal reaction on adrenalin 
and on adrenalin + serum. 
adrenalin + serum (Fig. 1g) yielded a still larger rise of the blood- 
pressure than 0.1 mgr. of adrenalin did without serum. Since in other 
cases the minimum dosis adrenalin on which a decapitated cat reacts 
lies between 0,005 and 0,0005 mgrms, the sensitivity to adrenalin 
of this cat was brought to normal values by the addition of human 
serum. Fresh cat's serum produced a weaker effect than human 
serum (Fig. 1h) in this experiment. 
In this first experiment it had thus been proved indubitably that 
in all probability human serum contains substances that intensify 
considerably the action of adrenalin on the decapitated cat. 
Now it is remarkable that in other 50 experiments we never 
achieved the same result. It is difficult to account for this; in per- 
forming this first experiment we did not know of course that it 
was an exceptional case, so we have not paid special attention to 
the problem in what respect this cat differed from others, whether 
it was a female or perhaps a castrated male, nor did we examine 
in any way the organs of internal secretion. For the present this 
question must therefore remain unsettled, and we must confine 
ourselves to the statement that in 50 other cases we never observed 
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