188 THE PITUITARY, THYROID AND ADRENALS AS A SYSTEM. 



blood-pressure, while simultaneously quickening the heart- 

 In -at. Howell 8 then ascertained that extracts of the infun- 

 dibular portion alone of the pituitary body gave rise to a 

 pronounced slowing of the heart, but with an increase of 

 blood-pressure. The latter rose more slowly than it did when 

 suprarenal extract was used, and sank gradually. Repeated 

 injections caused the effects to become less marked or to fail 

 altogether, especially when administered in rapid succession: 

 i.e., before a preceding injection had lost its effect (half an 

 hour or more). The organs affected appeared to have become 

 temporarily immune to the effects of the extract. De Cyon 7 

 also noted that slowing of the pulse accompanied the rise of 

 blood-pressure. Isaac Ott 8 even obtained this elevation of the 

 arterial tension in rabbits after severing the cord between 

 the atlas and occiput. Hinsdale 9 witnessed a rise of 11 milli- 

 meters Hg above normal (90 millimeters), followed by a decline 

 of 13 below normal, also in the rabbit. In a dog, it caused no 

 immediate change of pressure injected intravenously, but at 

 the end of an hour there had been a gradual fall of 10 milli- 

 meters. 



E. A. Schafer and Swale Vincent 10 found at least two 

 active substances, in extracts used by them, having distinct 

 physiological actions. From the one they obtained "a simple 

 rise of blood-pressure caused by contraction of the arterioles": 

 a fact ascertained by them "in the splanchnic area" and "not 

 very dissimilar to that caused by extract of medulla of supra- 

 renal." This pressure-raising substance is not soluble in alco- 

 hol. The second substance produced "a well-marked fall in 

 arterial pressure, the effect being almost identical in its char- 

 acters with that caused by cholin." 11 The marked fall of press- 

 ure could be obtained repeatedly at short intervals, thus dif- 



Howell: Journal of Experimental Medicine, vol. iii, No. 2, 1898. 



7 De Cyon: Archives de Physiologie, July, 1898. 



8 Isaac Ott: Medical Bulletin, Feb., 1898. 



Hinsdale: Loc. fit. 



10 E. A. Schafer and Swale Vincent: Journal of Physiology, May 11, 1899. 



11 In a foot-note the authors state that it cannot be cholin, since its action 

 persists after administration of atroplne, whereas they found that the depressant 

 action of cholin is prevented by atropine. It is evident, if the views outlined in 

 this work are correct, that the dose of atropine regulates the effect produced, 

 and that physiological tests of this kind are misleading, since all toxic symptoms 

 are due to the functional variations of the single set of organs the adrenals. 



