THE SUPRARENAL SYSTEM 185 



from the splanchnic nerve, and these undergo the maximum 

 degree of contraction. As Jonescu has pointed out, the renal 

 vessels are the first to contract, and this effect is produced by 

 doses which are too small to raise the pressure of the circulation 

 as a whole. If then, constriction within the splanchnic region gives 

 rise to a marked increase in tension, the increase in pressure will 

 produce a passive dilatation of the vessels in other parts of the 

 system, and this dilatation will be most pronounced in those 

 portions of the circulatory system which are not actively affected 

 by the constricting agent. Portions of the circulatory system 

 which are comparatively slightly affected by the vaso-constriction 

 are, apparently, the vessels of the extremities (passive increase in 

 the volume of the extremities has already been referred to), the 

 cerebral vessels and vessels of the retina, the pulmonary vessels, 

 and the coronary vessels of the heart. 



Spina showed that the intravenous injection of suprarenal 

 extract produces so marked a dilatation of the cerebral vessels, 

 that the opening of the dura mater may be followed by 

 hyperagmia amounting to cerebral hernia. But Biedl and Reiner 

 found that the cerebral vessels may be induced to contract by the 

 direct application of the agent. As soon, however, as the increase 

 in tension becomes general throughout the circulation, this 

 cerebral anaemia disappears as a result of the general high 

 pressure. That adrenalin causes the cerebral vessels to contract 

 was proved by Wiggers, who allowed Locke's fluid, to which 

 adrenalin had been added, to stream through the brain of a dog ; 

 he found that the liquid, after leaving the brain, was considerably 

 reduced in quantity. 



Velich was the first to discover the effects of suprarenal 

 extract upon the pulmonary circulation. He found that there was 

 a slight increase in pressure in the pulmonary artery, but believed 

 that this might be due to back pressure from the left auricle. 

 Direct inspection of the lungs showed that neither the intravenous 

 injection nor the direct application of adrenalin was followed by 

 the blanching observed in other organs under similar conditions. 

 Gerhardt also observed a slight increase in tension in the pulmon- 

 ary artery, and he ascribed it to the fact that, owing to the contrac- 

 tion of the systemic vessels, a larger amount of blood is carried to 

 the right heart. According to Gerhardt, the pulmonary vessels 

 are unaffected by suprarenal extract, and Brodie and Dixon were 

 unable to prove a vaso-constriction of these vessels after the 

 employment of adrenalin. They ascribe this result to inade- 

 quacy on the part of the vaso-motor innervation of the pulmonary 

 vessels. Plumier found that large doses were followed by distinct 

 vaso-contraction of the pulmonary vessels, and Petitjean arrived 

 at the same conclusion in regard to these vessels as Biedl and 

 Reiner in regard to the vessels of the brain. Petitjean believes 

 that adrenalin induces the pulmonary vessels to contract, but that 



