126 W. M. Bayliss and J. R. Bradford, 



riod, as determined aproximately from observations of a few cases, much 

 greater (about 2" — 3"), but as yet we have not made exact measure- 

 ments with a capillary electrometer. The following experiment well 

 illustrates the slow course of the variation: 



March 6th 1885. Sympathetic stimulated for' 70 " with coil at 5 c. 

 The unusually large deflection of 300 was obtained, this maximum 

 being reached 77" after the commencement of the stimulation; the 

 zero was regained, or almost so, rather more than 3 minutes after the 

 excitation had ceased. During this period two drops of a very viscid 

 saliva were registered in the manner described above, one 70" and 

 the second 150" after the commencement of excitation. In the same 

 dog excitation of the chorda with the coil at 12 c. and for a period 

 of 15 " caused the spot of light to fly off the scale and gave a copious 

 secretion of saliva. Hence although the sympathetic variation was a 

 very large one (as compared with the deflections usually obtained), 

 yet it was very much less than the chorda variation. In this case 

 the sympathetic deflection was nearly 80" in reaching its maximum, 

 and rather over three minutes in returning to zero, whereas the chorda 

 deflection caused the spot of light to fly off the scale 4" after the 

 commencement of the excitation. 



In this case, after the sympathetic stimulation, the galvanometer 

 did not return exactly to zero, and this is very frequently the case. 

 But occasionally the sympathetic deflection described above (i. e. outer 

 surface of gland positive) instead of returning exactly to zero, or 

 falling short of it by but a few divisions, actually passes beyond it, 

 so that a permanent after-effect is produced, of the nature of an in- 

 crease of the resting current (i. e. outer surface negative). Still more 

 rarely this after-effect occurs with such rapidity that we are compelled 

 to look upon it more as an excitatory variation than as an after-effect, 

 but this is not so frequent as the interesting second phase de- 

 scribed in the case of chorda-excitation. As will be seen from the ex- 

 periments quoted above, the stimulus necessary to excite the sym- 

 pathetic was of much greater strength than that for the chorda, 

 and it was only rarely that weak stimuli were found to be at all 

 efficacious. 



