1908. | Innervation in Vaso-motor Reflexes, ete. 353 
end of one of the lingual nerves, the other being cut, while the cervicab 
sympathetics were intact, was followed by constriction of the organ. Either: 
the conditions were not favourable, or the Lovén reflex on the tongue is a. 
matter of dilator excitation alone. The problem of these reflexes is still 
under investigation. | 
Piotrowski* has shown that excitation of the central end of the great. 
auricular nerve causes dilatation in the ear, whetner the sympathetic be 
divided or not. Since the latter normally possesses tone, there can be no. 
doubt that in the full reflex there is also inhibition of this tone.t 
III. Tue ACTION OF STRYCHNINE. 
It was discovered by Sherringtont that the inhibitory component of the: 
“flexion reflex” of the knee is converted by strychnine into an excitation. 
The phenomenon can only be satisfactorily explained by the hypothesis “ that. 
the action of the alkaloid is to convert in the spinal cord in these instances. 
the process of inhibition—whatever that may essentially be—into the process. 
of excitation—whatever that may essentially be.” 
As the depressor reflex is, at all events in great part, an inhibition of 
constrictors, Sherrington thought it of interest to test the action of strychnine 
on this; the result was that, in certain cases, a rise of arterial pressure was. 
produced, instead of the usual fall. Thinking the fact worth further investi-. 
gation, he suggested to me the continuation of the experiments. 
The subject proved to be more complex than it seemed to be at first sight,. 
but ultimately I found that all the various aspects of the action of strychnine. 
could be readily explained on the lines of Sherrington’s hypothesis, when the: 
nature of vascular reflexes, as described in the preceding pages, is duly taken 
into consideration. 
The effects of the actual injection of progressive doses of the alkaloid will - 
_be discussed in the first place. 
It is well known that a considerable rise of arterial pressure is caused by: 
the intravenous injection of a small dose. This is, no doubt, correctly 
- * *Centralbl. f. Physiol.,’ vol. 6, p. 464, 1892. 
+ Note added to Proof.—It is possible, according to a suggestion made by Professor 
Langley, that the dilator reflex in the submaxillary gland of the cat in response to 
excitation of the central end of the vagus, may be of the nature of a local, rather than. 
of a general, reflex. The vagus contains afferent fibres from the alimentary canal and it 
may be in response to excitation of these fibres that the vessels of the salivary gland are: 
~ dilated. If this is so, it should, perhaps, be referred to in the present section. In any. 
case, the reflex in question exhibits the phenomenon of reciprocal innervation, as shown: 
in a previous page. 
t ‘Roy. Soc. Proc.,’ vol. 76, B, p. 288, 1905. 
