ON THE VASCULAR SUPPLY OF SECRETING GLANDS. 459 



chorda by atropine, although the vaso-dilator hbr'es of the nerve remained 

 unaffected, and the secretion which can be obtained as a result of chorda 

 stimulation unaccompanied by vaso-motor changes after degeneration of 

 the nerve for two or three days. 



It cannot, however, be said that the problem of secretion has lost its 

 complexity even now, for we know that secretion may be accompanied by 

 \ aso-eonstriction or by vaso-dilatation ; that it may in .some cases bo 

 paralysed by quinine or atropine, in others not ; and that in the same 

 gland stimulation of one nerve may give rise to a secretion having quite 

 different characteristics from that brought about by excitation of another 

 nerve. 



In order to investigate the action of the chorda on the volume of the 

 submaxillary gland I have employed a plethysmograph of very simple 

 construction, devised by Professor 8chafer, which consists of a gutta- 

 percha box with one side of glass, thus enabling the gland to be kept 

 directly under observation, and any flushing or pallor of the superficial 

 vessels to be accurately noted. The vessels and gland-duct enter the box 

 on one side through an opening sufficiently large to prevent any pressure 

 being exerted upon them, and the rest of the aperture is closed by cotton- 

 wool and thick vaseline. Only a very small portion of the duct where it 

 emerges from the hilum is contained within the plethysmograph, and the 

 box is so supported by means of a clamp that the portion of duct outside 

 it is quite loose, and no contraction of the longitudinal fibres of the duct 

 can pull upon or otherwise affect the volume of the contents of tlie box. 

 The 1)ox is connected with a tambour or piston-recorder, which writes on 

 a smoked paper, by an indiarubber tube attached to a glass tube which 

 passes through one side of the box, the whole apparatus being filled with 

 air. A lateral tube leads from this connecting tube, and is closed with a 

 spring clip, so that the pressure within this air-tight system can be raised 

 or lowered at any moment. The tracings obtained in many cases show 

 most distinctly both heart-beats and respii-atory curves. 



The chorda was exposed after division of the digastric muscle, ligatured, 

 and cut, and the peripheral end stimulated by means of Ludwig's elec- 

 trodes, which were left in situ. In some cases, tlie chordo-lingual nerve 

 was divided centrally and the peripheral end stimulated ; any injury to 

 the more slender chorda through manipulation was thus avoided. The 

 nerve was excited by currents of different strengths, and with varying rates 

 of repetition of this stimulus, and the anaesthetic was varied in different 

 experiments. With a moderately weak stimulus excitation of the chorda pro- 

 duced considerable diminution in volume of the gland and a fall of the lever 

 of the piston-recorder. The fall was preceded by a short latent period when 

 the gland was secreting freely, and rapidly reached its maximum when 

 the stimulation was a short one. When the current was shut off the 

 lever still remained at its lowest point for a short time, which varied in 

 duration according to the length of passage of the current. The gland 

 then very gradually again increased in volume, and the lever rose until it 

 once more reached the base-line. This recovery in volume was succeeded 

 liy dilatation of the gland and further rise of the lever to a point well 

 above the base-line, after which it again gradually fell. The extent of 

 this dilatation varied according to the previous diminution in volume of 

 the gland, being greater and more prolonged when the diminution of 

 gland volume had been well marked, but the after-rise of the lever did 

 not equal in extent or duration its previous fall. This diminution in 



