1908. | Innervation in Vaso-motor Reflexes, ete. 365 
however, to paralyse the action of asphyxial blood than that which puts an 
end to the constrictor excitation from the median nerve. The following is 
the order in which the various effects dealt with in the preceding pages are 
attacked by the drug :— 
1. Constrictor excitation by median or other sensitory neive. 
2. Asphyxial excitation of constrictors. 
3. Dilator excitation by depressor. 
4. Constrictor excitation by reversed depressor. 
My experiments do not enable me to assign a place to the excitation of 
dilators by reversed median nerve effect. 
As to whether this difference of sensitiveness to strychnine implies a 
different point of attack in each case, I do not feel that we have yet sufficient 
knowledge of the way the result is produced to warrant an expression of 
opinion. 
‘TV. THe ACTION OF CHLOROFORM. 
In many of the early researches on vascular reflexes it was thought that 
the action of sensory nerves was of a depressor nature in the rabbit, until 
Cyon* showed that chloral, used as anesthetic for these animals, was 
responsible for the difference in behaviour compared with dogs. This 
observer, indeed, considered that the action of the drug was due to abolition 
of function of the cerebral cortex. The view cannot be maintained, since a 
far larger dose is required to convert the vaso-motor reflex than to paralyse 
the cortex. 1 have previously pointed outt that chloroform has the same 
effect, and is more convenient in practice, since the experiment can be com- 
menced under ether, in order to obtain the pressor reflex, which can then be 
converted by administration of chloroform ; if desired, ether can be returned 
to and the original form of the reflex obtained. 
In experiments with chloroform, the difficulty to be contended with is the 
paralysing action of the drug on the heart, and, in fact, on all protoplasinic 
activities. The arterial pressure being low, the centres suffer from anemia, 
so that the reflexes obtained are usually small. 
Fig. 24 was obtained from a rabbit, in which a plethysmographic tracing 
was given by the kidney. Im the first curve, under ether, excitation of the 
median produced the typical pressor effect of rise of blood-pressure with 
constriction of the kidney. Chloroform was now given until the arterial 
pressure was reduced from 110 mm. Hg to 64 mm.; on repeating the 
excitation a fall of pressure was seen, accompanied by dilatation of the 
* ‘Bulletin de Acad. des Sciences de St. Petersburg,’ December 22, 1870. 
+ ‘Journ. of Physiol.,’ vol. 14, p. 316, 1893. 
