392 



Mr. D. T. Harris. 





Flow of blood. 



Oxvgen used. 



During rest 



Stimulation of lingual nerve 



c.c./min. 

 0-59 



2-85 



c.c./min. 

 144 



-142 



From this it will be seen that the stationary oxygen consumption lends no 

 support to the metabolite theory for the explanation of the five-fold increase 

 of blood flow obtained by these experimenters. 



Measurement of the alkali reserve of the blood from the lingual vein and 

 the blood from the femoral artery during stimulation of the lingual nerve 

 shows them to be practically identical. This is seen in the following figures, 

 obtained from different dogs under widely varying conditions: — 



Stimulation of lingual 

 nerve. 





Alkali reserve 



of plasma. 





Lingual rein 



49 5 



53-5 



67-0 



69 



70 



48-5 



Femoral artery 



49 -5 



54 -0 



67 o 



69 



70 



49 



Thus, interrupted faradisation of the lingual nerve produces no measurable 

 difference in the alkali reserve (CO2 metabolite), even when the vaso-dilation 

 is so great as to increase the blood-flow five to eight times, as in the above 

 experiments (of course, the dilution of the metabolite proceeds at the same 

 rate). In so far as gaseous metabolites are concerned, there is no denying 

 the existence of vaso-dilator nerves. 



Furthermore, no real difference was detected in the lactic acid-content of 

 the blood issuing from the tongue during stimulation of the lingual nerve as- 

 compared with that in the arterial femoral blood, e.g., femoral artery, 

 6'4mgrm. per 100 c.c. ; lingual vein, 6 - mgrm. per 100 c.c. 



If vaso-dilator substances are produced when the lingual nerve is excited, 

 then they must necessarily be of a non-oxidative character and presumably of 

 a very powerful nature ; the later stages of this investigation will show that 

 such an assumption is unnecessary, since the vaso-dilator nerves of the 

 tongue possess independent functions, and are not subservient to the func- 

 tional activity of the tongue muscles. 



The glossopharyngeal, the sensory nerve of the posterior third of the 

 tongue, responds to stimulation just as the lingual does, but in a milder 

 degree (fig. 8) ; either it contains specific vaso-dilator fibres (via tympanic 

 branch, Loeb and Eckhard), or it is capable of conducting anti-dromic vaso- 



