460 REPORT— 1900. 



gland volume was accompanied by a free flow of secretion from the duct, 

 the amount of which was measured, and by marked dilatation of the 

 ^'essels of the gland. 



With a stronger stimulus the latent period was shorter, the flow of 

 saliva greater, and the diminution in volume of the gland more abrupt 

 and of greater range. The recovery of volume was also slower, and the 

 after dilatation more marked. When the excitation was a long one, more 

 especially with a strong current, the recovery of the gland was consider- 

 ably prolonged, and the rise of the lever a very gradual one. As long as 

 both gland and nerve remained in good condition successive stimulations 

 of the chorda repeated as soon as the gland had returned to its original 

 volume still continued to produce the same effect, with but little difference 

 in diminution of volume in response to stimuli of the same strength and 

 duration. If, however, the nerve was stimulated a second time, either 

 immediately after the first excitation or while the lever was still rising, 

 the resulting diminution in volume of the gland was less than that pre- 

 ceding it, this difference being greater the more quickly the second 

 excitation succeeded the first. When the secretion produced by chorda 

 stimulation was scanty and viscid, in spite of the accompanying active 

 vaso-dilatation, stimulation of the nerve caused either a very small fall 

 of the lever or a preli)ninary fall succeeded by a rise. In some cases, 

 more especially when there was some obstruction to the free escape of 

 blood through the veins, and also scanty secretion, chorda excitation gave 

 rise to increase of volume of the gland, owing to the increased flow of 

 blood to the gland more than compensating for the small amount of 

 secretion leaving it. After the administration of small doses of atropine 

 intravenously, sufficient to paralyse the secretory fibres of the chorda 

 (8-12 mg. for a dog of 7 kilos.), stimulation of the peripheral end of the 

 divided chorda caused no flow of secretion from the duct, Ijut an active 

 dilatation of the gland and a rise of the piston-recorder lever to an extent 

 about equal to the previous fall of the same lever brought about by a 

 stimulus of the same strength and duration before any atropine had been 

 administered. 



The absolute increase or diminution in the volume of the gland under 

 various conditions was estimated by calibration of the piston-recorder, 

 the rise or fall of the lever for fractional parts of a cubic centimetre 

 being marked out on a scale. The volume of the gland in cubic centi- 

 metres was determined from the diff'erenoe between its weiglit in air and 

 in water, and the amount of secretion produced by nerve stimulation or 

 otherwise was also determined by connecting the cannula in the duct with 

 a glass tube graduated in fractional parts of a c.c. In order to determine 

 the total diminution in volume of the gland, due to chorda stimulation, 

 the diminution in volume of the gland was first detei'mined in an etherised 

 dog before the administration of atropine, and then the increase in 

 volume of the same gland after the administration of a dose of atropine 

 sufficient to paralyse the secretory fibres of the chorda. By adding the 

 two amounts together the total loss of gland contents due to chorda 

 stimulation was obtained. On comparing this with the amount of secre- 

 tion poured out in the same time we found that at least -,"^ of the 

 seci-etion was derived from the extra-vascular portions of the gland. 

 Since there is no diminution in the lymph flow from the gland, but rather 

 a slight increase during the period of stimulation (Bainbridge), we must 

 conclude tli^t the effect of the secretory nerves is simply and solely upon the 



