296 MATHEWS. 



the pressure of the blood even in the carotid artery. They 

 thus demoHshed, once and for all, the filtration theory. They 

 found, further, that the temperature of the saliva secreted from 

 the dog's submaxillary might surpass by i.5°C., the temperature 

 of the blood in the carotid artery,^^ and as final evidence that the 

 chorda tympani could induce secretion independent of the vaso- 

 motor action, they brought forward the observation that stimu- 

 lation of this nerve still caused a secretion, some minutes after 

 the heart ceased to beat.^^ It is not strange that, in the face of 

 such facts, Ludwig should have felt compelled to assume the 

 secretory activity of the gland cell. 



Heidenhain soon added other facts pointing in the same di- 

 rection. He found that if the blood supply be cut off from the 

 submaxillary gland by compression of the artery the chorda 

 still caused a secretion analogous to the post-mortem secretion 

 after the heart ceases to beat.^^ Giannuzzi^"^ discovered that by 

 the injection of sodium carbonate or a dilute solution of hydro- 

 chloric acid into Wharton's duct a pronounced vaso-dilation en- 

 sued, on stimulation of the chorda, but no secretion. Heiden- 

 hain-'^ found that quinine sulphate injected into the duct had a 

 similar action, and that atropine"^ effectually paralyzed secretion, 

 while leaving the vaso-dilator power of the nerve unaltered. 

 Heidenhain-'^ also discovered, and Langley confirmed his obser- 

 vation, that after the chorda tympani had been paralyzed by the 

 action of nicotine, either injected subcutaneously or applied di-, 

 rectly to the submaxillary ganglion, the chorda tympani recov- 

 ered its secretory function before its dilator function. He 

 observed, also, that after the chorda had been cut and allowed 

 to degenerate for 2-3 days stimulation of the nerv^e still caused 

 an increase in secretion, without an increase in the flow of blood 

 from the gland's vein. This evidence show^ed that vaso-dilation 

 might ensue 'without a secretion, that secretion might take 

 place unaccompanied by vaso-dilation, and that secretion might 

 be caused by stimulating dilator nerves after cutting off the 

 blood supply. If these facts were true vaso-dilation cou]d not 

 be the cause of secretion, and hence that cause must be sought 

 in some other gland element than the blood vessels. 



