THE PITUITARY BODY 



813 



vessels, still produces a stimulating effect on the excretion of urine. 



The work of Knowlton and Silverman 58 on the gaseous exchange of the 

 kidney during pituitrin diuresis is against this view. These observers 

 could detect no increased oxygen consumption accompanying the in- 

 creased urinary flow, and ascribe the latter effect purely to augmented 

 blood flow. The value of pituitrin as a diuretic in clinical practice is now 

 well recognized. 



The work of Cow 52 upon the secretory activity of the kidney in rela- 

 tion to pituitrin administration indicates that the hypophysis normally, 



Fig. 200. Tracing showing the constricting action of pituitrin on the bronchioles and its effect 

 on blood pressure in a spinal dog. (From Jackson.) 



is part of a mechanism for the control of the urinary flow its action 

 being opposed to that of the adrenal medulla. It is asserted that ingested 

 fluid taken up by the gastrointestinal mucosa absorbs a substance of a 

 hormonic nature contained therein, which passing into the general blood 

 stream calls forth the diuretic principle from the pituitary body. 



The effect on milk secretion is best demonstrated by placing a cannula 

 in the mammary ducts so that the milk may freely flow out. By observ- 

 ing the rate of outflow during the injection of pituitrin, it will be found 

 that a remarkable increase occurs. After this increased secretion has 

 ceased, however, the injection of more pituitrin has no further effect, 

 indicating that the influence of the first injection must have been, not so 



