16 THE PHYSIOLOGY OP THE ADRENALS. 



they concluded that there had been a strong constriction of 

 the small arteries: strong in their sense, meaning the relative 

 constriction as compared to that of other vessels. This is fully 

 accounted for by the greater relative supply of muscular tissue 

 in these peripheral vessels. As is well known, arteries are 

 endowed with a coat of muscular fibers, which assumes in- 

 creased thickness and relatively greater mechanical power as 

 the capillaries are approached; so that in the smaller arteries 

 the muscular layer is relatively quite thick. Isaac Ott 52 re- 

 peated the test with a Ludwig kymograph and reached the 

 same conclusion. 



That all organs are similarly affected owing to their vas- 

 cular supply was also shown by Oliver and Schafer by means 

 of the plethysmograph, not alone the limbs, but such organs as 

 the spleen and the kidney being contracted from 20 to 25 per 

 cent, after intravenous injections of the extract. These ex- 

 periments also showed that great vascular constriction in the 

 splanchnic area was caused. Veins, we have seen, are likewise 

 constricted by suprarenal extract; they also contain muscular 

 fibers in their thinner walls. Although the supply of muscular 

 elements is less important than in the arteries, this is, to a 

 degree, compensated by the greater lumen. That the entire 

 vascular system of the organism is thus acted upon by the 

 suprarenal specific principle, owing to the muscular tissues 

 which it contains, is beyond question. 



Can we conclude from these data that the vasomotor sys- 

 tem is never influenced by the suprarenal extract, in view of 

 the fact that the blood-pressure is as actively increased by it 

 when the bulb and the cord have been removed or severed? 

 Such a deduction is hardly warranted, since the vasomotor sys- 

 tem as a source of stimuli (unlike the inhibitory action referred 

 to, which must obviously withhold stimuli) might, in a normal 

 animal, contribute to the general vascular contraction and 

 perhaps be its main source. Indeed, it is probable that the 

 injected extract does, in an animal deprived of its cord, what 

 it would not do in a normal animal: i.e., find its way into 

 the blood-vessels, owing to the general vascular dilation caused 



62 Isaac Ott: Medical Bulletin, Jan., 1898. 



