HYPOPHYSIS CEREBRI 323 



activity or by pulmonary oedema. After repeated exhibition of 

 small quantities of the substance there was a marked loss in 

 weight. The phenomena which Urechia observed after the rein- 

 jection of pituitary extract after an interval of ten days, were 

 probably anaphylactic in character. 



According to Delille, there is an essential difference between 

 the toxic action of the anterior and the posterior lobes, the toxicity 

 of pituitary extract being principally or even exclusively the 

 property of the posterior lobe. 



THE PHYSIOLOGICAL ACTIVITY OF PITUITARY 



EXTRACT. 



It was first ascertained by Oliver and Schafer that the injec- 

 tion of extract of the hypophysis into the veins produces a prompt 

 and very marked increase in arterial pressure ; this differs from 

 that produced by suprarenal extract in its duration, which is 

 longer by several minutes. This hypertension results, partly from 

 contraction of the vessels, and partly from increased cardiac 

 activity, and it is not disturbed by resection of the cord or of 

 the medulla. The peripheral effect of this hypertension is illus- 

 trated by the fact that, if a fluid containing pituitary extract is 

 circulated through the hinder extremities of frogs, there is a 

 marked reduction in the venous outflow. The increased cardiac 

 activity was shown in the myographic curve which Oliver and 

 Schafer obtained with the heart after its removal from the living 

 body. 



The effect of pituitary extract upon the circulatory apparatus 

 is, in many respects, analogous to that of suprarenal extract, 

 though it differs in certain important particulars. The vaso-con- 

 strictor action is much slighter, and the marked slowing of the 

 pulse, together with inhibition of auricular contraction, produced 

 by suprarenal extract where the vagi are intact, is absent in the 

 case of pituitary extract. On the other hand, after resection of 

 the vagi, pituitary extract produces, not an acceleration, but rather 

 a retardation of the cardiac beats. 



The findings of Oliver and Schafer were confirmed in all 

 important particulars by later investigators. Howell next dis- 

 covered that the substance which produces vaso-constriction and 

 slowing of the pulse is principally contained in the extract of the 

 posterior lobe, the pars nervosa. He also discovered the remark- 

 able fact that a second injection, given half to one hour after 

 the first, has practically no effect upon the circulation. Howell's 

 findings were confirmed by Schafer and Vincent, who discovered, 

 further, that the second injection is followed by a fall, instead of 

 a rise, in blood-pressure. According to these authors, the fall in 

 pressure is brought about by the action of a second substance with 

 depressant properties, which is obtainable by extraction with 



