140 



Chapter IX 



chorda tympani, i.e. dilatation. Now this is precisely what does not 

 take place. Administer ergotoxine in a suitable dose, stimulate the 

 cervical sympathetic either with an induction current or with adrenalin, 

 and you do not get dilatation; the effect of the excitation of the 

 nerve upon the vessels of the gland is nil. Nor is there any secretion 

 of saliva. The assumption that this dilatation is due to dilatator 

 fibres has therefore broken down. The rival theory holds the field. 



To leave the matter at this point would be unsatisfying. It is 

 desirable that the theory of chemical, or as I prefer to call it 



113. 



FIG. 76. 



^^ = Arterial pressure. 



= Kate of flow of saliva in c.c. per minute. 



= Bate of blood-flow through vessel of submaxillary drawn to one-tenth of the scale 

 of the saliva curve. 



"functional," dilatation should stand not merely by default. There 

 should be actual proof that (1) the metabolism of the submaxillary 

 gland is increased when the sympathetic is stimulated, and (2) that 

 the actual metabolic products present are such as have the power 

 of dilating vessels. 



What evidence, then, is there of increased activity of the tissues 

 in the gland when the sympathetic is stimulated ? 



The answer can best be obtained when the sympathetic is stimu- 

 lated by means of intravenous injection of adrenalin, for when a 



