360 Dr. W. M. Bayliss. On Reciprocal [Jan. 20, 
attempting to completely reverse the depressor action. For, supposing that 
before strychnine the usual effect on the limb was obtained, viz., a dilatation, 
and that after a certain dose of the drug there was a diminution of volume of 
the limb but coincident with a fall of arterial pressure, the objection would 
justly be made that the diminution of the leg-volume was merely the passive 
effect of the fall of pressure, the proper depressor effect of dilatation being 
paralysed. Moreover, the absence of a dilator reflex on repetition of the 
stimulus is by no means uncommon. For this reason I am unable to admit 
that the mere non-appearance of a dilator reflex is of any value as evidence. 
The result of the experiment of fig. 18 is conclusive in showing that the 
reversal of the normal depressor fall into a rise is a matter effected by the 
constrictor system and since in normal conditions the depressor inhibits this 
system, it inevitably follows that, by some 
means or other, the inhibitory action is 
changed into an excitatory one. 
When I demonstrated the rise of pressure 
from the depressor after strychnine at the 
Nie, 
fp ee 
an 
AN WWWy WW 
we International Congress of Physiologists at 
ie Heidelberg in 1907, Professor Hans Meyer 
made the criticism that the result might be 
: ie due to escape of exciting current to neigh- 
bouring tissues, whose reflexes would be more 
Fic 18 Eee eek ee easily evoked under the alkaloid, while the 
constrictors toleg by depressor action of the drug on the depressor reflex 
after strychnine. Uppercurve, might be merely that of paralysis. I was 
volume of leg. Lower curve, 
able to show that the same result was obtained 
arterial pressure. 
by pinching the nerve with forceps. It is also 
easy, by placing electrodes on the surrounding tissues, to show that the 
suggested explanation is not the correct one; this has no effect at all when 
the reversal is at its maximum. Indeed, excitation of the trunk of a nerve 
such as the median at this stage, or even earlier, has no effect on the blood- 
pressure, a fact which disposes also of another possible explanation of the 
reversal. This consists in the hypothesis that there are in the depressor trunk 
a certain number of pressor fibres which come into effect when the depressor 
fibres are paralysed by the drug. 
On proceeding to further investigate the action of strychnine on pressor 
reflexes, some interesting facts came out. I have already mentioned that very 
early in the progressive poisoning these reflexes are abolished, so that no 
effect of any kind is produced in the curarised animal by exciting a pressor 
nerve. This statement, however, only applies to the complete animal. 
