The regulation of the supply of oxygen to the tissues 141 



faradic current is used, the issue is complicated by the fact that 

 the blood is almost entirely cut off from the gland at times, but with 

 stimulation by means of adrenalin all is in our favour ; we get a good 

 flow of saliva, a good dilatation, and the effect of the primary con- 

 striction, as far as rate of blood-flow is concerned, is largely counter- 

 balanced by the increased arterial pressure. The experiments were 

 performed on cats. A graduated tube was fixed into Wharton's duct ; 

 an observer registered the rate of flow of saliva on the kymograph 

 with a signal and tapping key. The blood from the gland was collected 



F IG . 77. A and B form continuous portions of a single tracing. From above downwards 

 (1) arterial pressure, (2) time of injection of adrenalin, (3) each mark of the signal sig- 

 nifies the flow of 0-01 c.c. of saliva, (4) blood signal marks correspond to O'l c.c. 



in a cylindrical 1 c.c. pipette placed horizontally, the pipette was 

 graduated in tenths of a cubic centimetre and the moment at which 

 the blood meniscus passed each graduation was also recorded. The 

 general arterial pressure was registered from the femoral artery. 

 Samples of arterial blood for comparison with the blood from the 

 gland were obtained from the other femoral artery. The figure given 

 below shows the general time relations of the experiment, while we 

 have seen in Chapter VI that there is a great increase in the 

 metabolism of the gland as shown by the oxygen used up. 



