The regulation of the supply of oxygen to the tissues 143 



Cat killed with chloroform about 11 a.m. perfused with warm Ringer's fluid. 



11.48 30, 30, 30 drops per half minute. 

 11.50 Inject 1 c.c. pilocarpine. 



44, 44, 45. Saliva. 



37, 37. Saliva stops. 



38 \ 



No saliva. 



11.53 

 12.22 

 12.25 

 12.31 

 12.34 

 12.45 

 12.49 

 12.55 

 12.55-30 9, 10, 10, 10. 



The same gland next day : 

 10.19 20, 18, 18, 16, 17. Inject adrenalin. 4, 3, 3, 4, 3, 3. 



36 

 36 

 36 

 36 

 Inject 1 c.c. adrenalin. 



No saliva. 



FIG. 78. Effect of injecting adrenalin on the rate of blood-flow of submaxillary gland. 

 A normal, B after clamping artery for 1 hour and 50 minutes. 



We need not, however, have resort to artificial perfusions in order 

 to find out that adrenalin does not cause dilatation but constriction 

 when the gland is incapable of secreting. It is only necessary in the 

 living animal to clamp the submaxillary artery, wash out the gland 

 with cold saline, and leave it so for a couple of hours ; at the end of 

 this time the circulation of blood is reestablished. On the injection 

 into the arterial stream, close to the origin of the submaxillary artery, 

 of 0'5 c.c. of adrenalin*, we find that constriction only ensues 



and that no saliva is secreted ; under normal circumstances saliva 



* The adrenalin comes out from the gland with the blood whose rate of flow 

 is being measured, and so never reaches the general circulation. 



