THE ADRENAL BODIES 221 



during splanchnic stimulation is greater than that of the same 

 blood under normal conditions. He looks upon the splanchnic 

 as a true secretory nerve for the adrenal body. 



After the very important discovery that adrenal extracts 

 raise the blood-pressure, there was a growing tendency to 

 assume that the function of the adrenal (or, at least, of its 

 medullary portion) is to help to maintain the normal blood- 

 pressure and to keep up the tone of sympathetically innervated 

 structures in general. The present writer was one of the first 

 to grow suspicious on this point. If the constant secretion of 

 adrenin into the blood-stream and its action upon the sym- 

 pathetically innervated vascular muscle is an important factor 

 in the maintenance of the normal blood-pressure, then it ought 

 to be possible by tying or clamping the veins issuing from the 

 glands, to keep down the blood-pressure at a low level during 

 the period of clamping or tying, and to allow it to reach its 

 normal level on releasing the clamp or the ligature. Some 

 writers have claimed that they have obtained this result. Such 

 has been definitely recorded by Strehl and Weiss, who extir- 

 pated the adrenal body on one side, and found that when a 

 clamp was put upon the adrenal vein of the other side the 

 blood -pressure immediately fell, and rose again when the clamp 

 was released. Their experiments were performed upon rabbits. 

 They gave a tracing which shows a very marked depression 

 during the period of the clamping of the vein. 



Kretschmer finds that if adrenalin solution is injected intra- 

 venously into rabbits each new dose produces a rise of pressure, 

 and between the doses the pressure falls to normal owing to the 

 rapid destruction of adrenalin in the body. For this reason 

 repeated injections cannot keep up the blood-pressure, but 

 continuous injection can do so. The action on the blood- 

 pressure lasts just so long as there is any adrenalin in the blood. 

 According to Kretschmer, the continuous internal secretion of 

 adrenalin from the adrenal bodies is probably of significance 

 for the maintenance of the normal vascular tone. If, as in 

 vitro, the destruction of adrenalin in the body is dependent on 

 the amount of alkali present, then should intravenous injection 

 of alkali cause a lowering of blood-pressure due to a breaking 

 down of the continuous supply of adrenalin. A lengthening of 

 the action of adrenalin is in fact produced experimentally by a 

 simultaneous injection of nitric acid. 



