244 INTERNAL SECRETION 



brought about by the agency of many substances which do not 

 raise pressure, if these are administered in a suitable manner. 

 Such substances are : normal saline solution in large quantities ; 

 hydrochloric, phosphoric, and lactic acids; calcium phosphate r 

 potassium bichromate, uranium nitrate, chloral amide, phlorizin, 

 trypsin, pepsin, thyroidin, and dried mammary gland. It 

 must be conceded, however, that these substances never produce 

 changes as marked as those which result from the action of 

 adrenalin. 



The toxo-chemical action of adrenalin is still further proved 

 by the results of Falk's experiments. While ignoring the rise in 

 blood-pressure produced by adrenalin, he succeeded in intensify- 

 ing or reducing the arterial changes which followed it by 

 injecting, together with adrenalin, substances which have no 

 influence upon blood-pressure, their action being purely 

 chemical.* According to Falk, a repeated, transitory rise in 

 pressure and functional hyper-stimulation of the muscles of the 

 vessels, are essentially the predisposing causes of necrosis of the 

 vessels. " High blood-pressure alone never gives rise to serious 

 injury of the media, that is to say, to regressive changes ; for 

 hyperactivity is, in itself, far more likely to lead to a gradual 

 hypertrophy of the various layers forming the walls of the vessels. 

 It is in this way that Falk explains the results of experiments in 

 w 7 hich changes in the vessels, in every way resembling those 

 provoked by adrenalin, w^ere brought about by repeated mechanical 

 hypertension induced by the injection of gamboge or croton oil, 

 w 7 ith simultaneous compression of the abdominal aorta. 



In company with L. Braun, I investigated the effect which 

 purely mechanical hypertension exercises upon the vessels. We 

 found that, in the rabbit, sheep, and ape, repeated compression of 

 the aorta above the point of departure of the renal artery gives 

 rise to lesions of the vessels, which upon the whole, are analogous 

 to those produced by adrenalin. From the results of experiments 

 carried out under special conditions, we concluded that the 

 vascular lesions depend, not only upon the hypertension, but also 

 upon the extreme pressure fluctuations which take place in the 

 arterial system, and w r hich make special demands upon the 

 elasticity of the vessel walls. f 



* The arteriosclerosis was either prevented or arrested by the simul- 

 taneous injection of chemotaxic substances, such as : dead staphylococci, 

 pyocyaneusprotein, oil of turpentine, aleuronate, and sesame oil ; it was 

 enormously increased by the subcutaneous injection of croton oil, gamboge, 

 and bacterial toxins. Falk thinks that the absence of arteriosclerosis is due 

 to the increase in the amount of lymph. After Biedl and Offer had proved 

 that the glocosuric action of adrenalin is inhibited by lymphagogue sub- 

 stances, Falk found that the injection of extract of leeches, which increases 

 the circulation of lymph, was likewise unattended by changes in the 

 vessels. 



t A detailed account of " compression sclerosis " as observed by Braun 

 and myself appeared in the Sitzungsberichten der k. Akad. d. Wissensch. 

 in Wien. Vol. 119. 191 1. 



