KELATION SUPKAKENAL GLANDS TO CIRCULATION 221 



what extent the volume reactions in the intestine might be dependent upon 

 back pressure from the liver. To answer the question several dogs were 

 tested before and after the production of an Eck fistula. It was found that 

 shunting the portal blood directly into the vena cava ordinarily made no 

 perceptible difference in the gut volume or venous outflow reactions. The 

 liver, therefore, played no essential role. 



More recently Erlanger and Gasser (1919) have recorded some further 

 observations on the effects of epinephrin in the splanchnic area. Their 

 studies took account more particularly of the effects on the rate of blood 

 flow in the various organs. They concluded that the effect is invariably 

 vasoconstriction. In some cases this was so marked as to bring about 

 almost complete stoppage of the blood. The discrepancy between their 

 observations and those of the previous observers is supposedly to be as- 

 cribed to the fact that they used such enormous doses as 10 mg., that is, 

 approximately a hundred times as great as those used in the earlier re- 

 searches. Such data are obviously of merely pathologic, not physiologic, 

 significance. 



The available data as a whole do not permit any very satisfactory 

 generalizations regarding the effects of epinephrin on the intestinal circula- 

 tion. On teleological grounds one would expect the administration of the 

 drug to result in vasoconstriction, since it produces (except in very minute 

 doses) a striking inhibition of peristalsis; as a general rule, a quiescent 

 organ receives a diminished blood supply. Furthermore, if, as Cannon 

 maintains, epinephrin serves normally to integrate the body for strenuous 

 muscular activity, this would be subserved by a shifting of the blood from 

 the splanchnic area in general to the more active tissues. 



It is possible that the dilatation reactions observed in the gut by some 

 investigators may have been due to the employment of experimental 

 methods inadequate to deal satisfactorily with the somewhat complicated 

 circulatory conditions involved. It is possible too that merely opening the 

 abdomen and manipulating the intestines ,may introduce such perturba- 

 tions of the delicate physiological adjustments as to lead to anomalous 

 results. In any case the problem needs further study. Erlanger and 

 Gasser's inflow method, with proper attention to dosage, would perhaps 

 be most likely to afford convincing data. 



It is generally assumed, though without definite proof, that the cir- 

 culatory reactions to epinephrin in the stomach parallel those in the in- 

 testine. It is also assumed that reactions in the large and the. small 

 intestine are similar. Both these assumptions should be put to the ex- 

 perimental test. 



Effects on the Circulation of the Brain. In view of the fact that 

 the brain is incased in the rigid cranium, it can dilate or contract only as 

 cerebrospinal fluid is displaced into or from the spinal canal. This can 

 occur only to a very limited extent. Hence, gross vasomotor reactions to 



