382 Mr. J. N. Langley and Mr. W. L. Dickinson. [Mar. 27, 



of the region is not the same ; and from the unequal effects on 

 different dogs we may probably conclude that the proportion of the 

 two kinds of nerve fibres varies somewhat in different individuals, 

 although it is possible that the results on which this conclusion is 

 based may be caused by a temporary variation in the condition of the 

 animal, for example, in the amount of anaesthetic given. 



It was noticed by Bochefontaine and Vulpian and also by Dastre 

 and Morat that in the cat and rabbit pallor, and not flushing, of the 

 bucco-labial region is caused by stimulating the cervical sympathetic. 

 Like these observers, we have not seen primary flushing with any 

 strength of stimulus ; the pallor is marked, except when, for any 

 reason, the gums and lips are already pale ; as a rule there is no 

 marked after-flush, but the mucous membrane slowly regains its 

 normal tint. On repeated stimulation of the sympathetic the bucco- 

 labial region remains pale and shows very little alteration. In the 

 course of our experiments upon the dog, we had occasionally seen a 

 slight paling or flushing in the lips and gums on the side opposite to 

 that on which the sympathetic was stimulated ; in the cat and rabbit 

 we have paid more attention to this effect, and we find that in these 

 animals, stimulation of the sympathetic produces a bilateral effect. 

 The pallor on the opposite side to that on which the nerve is stimu- 

 lated is greater in the rabbit than in the cat, and is more obvious in 

 the gum of the anterior part of the lower jaw than elsewhere. The 

 degree of the pallor on the opposite side varies considerably in different 

 individuals. Occasionally in the rabbit the pallor is complete on 

 both sides, but in most cases it is much more marked on the side on 

 which the nerve is stimulated. The bilateral action occurs with either 

 sympathetic, although it may be more marked with one sympathetic 

 than with the other ; it occurs with all strengths of currents that 

 produce any effect ; it is best seen at the beginning of an experiment, 

 for after repeated stimulation of the sympathetic the paling on the 

 opposite side becomes less distinct, and it is much better seen in the 

 anterior than in the posterior part of the lips and gums. In the 

 rabbit a little care must be taken not to stretch the lips too much 

 during the experiment, since this of itself may cause some pallor in 

 the gums. We have also seen some bilateral pallor in the tongue, 

 especially in the tip on stimulation of one sympathetic ; but we have 

 paid attention to this in a few experiments only. 



Experiment I. 



Rabbit (C. p. 34). Chloral. Chloroform and ether. Sec. coil at 9 gives shocks 

 rather weak to tongue. 



12.13. Tie and cut left sympathetic (separated from depressor) in middle of 

 neck. 



Stim. sy., c = 9, for 20 sees, j bilateral pallor in upper and lower lips; in 



