184 INTERNAL SECRETION 



frequently produces only toxic effects, such as fluttering or sudden 

 arrest of the heart, and occasionally cedema of the lungs. 



These conditions militate to a certain extent against an 

 accurate estimation by means of blood-pressure readings, of the 

 quantitative value of adrenalin solutions. The presence of an 

 amount less than .001 mg. in i c.cm. cannot be proved with 

 certainty by means of animal experiments. The approximate 

 values of solutions containing a larger proportion of adrenalin 

 may be estimated by means of dilution. 



The effect of adrenalin in raising blood-pressure is primarily 

 the result of vaso-constriction, that is to say, of a contraction of 

 the walls of the peripheral blood-vessels. This constriction of 

 the blood-vessels is clearly shown by the pale colour of the mucous 

 membranes. By means of oncometric experiments, Oliver and 

 Schafer ascertained the volume of the different organs. They 

 found that the abdominal viscera supplied by the splanchnic 

 nerve, such as the spleen, kidney, and intestine, become con- 

 siderably reduced in volume ; while the volume of the extremities 

 becomes increased, owing to the rush of blood into them from 

 the splanchnic region. A. Velich found by direct inspection that 

 there was a distinct reduction in the volume of the intestine, 

 kidney, and conjunctiva. 



With regard to the origin of this peripheral vaso-constriction, 

 Cybulski and Szymonowicz assumed that it resulted from stimu- 

 lation of the central vaso-motor apparatus in the medulla 

 oblongata. But other experiments have shown that suprarenal 

 extract produces an enormous rise in blood-pressure after resec- 

 tion high up the spinal cord and destruction of the medulla (Oliver 

 and Schafer), after destruction of the entire central nervous 

 system (Biedl, Velich), and after resection of both splanchnic 

 nerves (Boruttau). I have kept the arterial pressure of animals 

 in which the central nervous system was entirely destroyed, at 

 140 to 160 mm. Hg. for hours at a time, by means of continuous 

 transfusion of a diluted solution of suprarenal extract. The rise 

 in blood-pressure also takes place where, as the result of profound 

 chloroform or chloral anaesthesia, the intervention of the central 

 nervous system is excluded (Gottlieb). That the vaso-motor 

 nerve-centres play a part in the production of the vaso-constriction 

 cannot be denied, if the quantitatively stronger action in the 

 sound animal, and the increased pressure which immediately 

 follows the direct introduction of adrenalin into the cerebral 

 circulation (injection into the carotid towards the brain, Biedl 

 and Reiner) are taken into account. It is probable that the 

 stimulation of the vascular centre is not direct, but is a secondary 

 effect brought about by the local anaemia. 



The vaso-contraction does not affect all parts of the system 

 equally. The introduction of adrenalin into the general circu- 

 lation affects primarily those vessels whose innervation proceeds 



