1909.] 



The Functions of the Pituitary Body. 



447 



differentiate between the action of the different parts of the gland, having 

 used extracts of the whole pituitary body. 



Howell (1898) carried the investigation further, and added considerably 

 to our knowledge of the action of extracts of the gland. He split it 

 into anterior and posterior parts, and determined that whilst the extract 

 of the former is without physiological activity when injected into a vein, 

 that of the latter produces the effects upon blood-pressure and blood- 

 vessels which Oliver and I had obtained from extracts of the whole gland. 

 Howell further found the rise of blood-pressure to be accompanied by a 

 slowing in the action of the heart, and that both the raised blood-pressure 

 and slow cardiac rhythm might be maintained for a considerable time. And 

 that if a second dose be administered intravenously within a certain time — 

 which varies from half an hour to an hour or more — after the first dose, 

 these effects are not repeated — in other words, a certain immunity is 

 established which only slowly passes off. 



Swale Vincent and I (1899) repeated Howell's observations. We were 

 able to confirm them in almost every particular, but found that the cardiac 

 slowing described by Howell is not constant, and that when present it is 

 not abolished by section of the vagi or the action of atropine. It is, 

 therefore, of peripheral origin, and not due to the same cause as the 

 inhibition which often accompanies the action of adrenin, which is brought 

 about by an action upon the cardio-inhibitory mechanism in the bulb. We 

 also found that not only is there generally no rise of blood-pressure resulting 

 from a second or third dose of the extract of posterior lobe, but there is 

 invariably a fall, which, however, lasts only a short time. We showed 

 that this fall of blood-pressure is due to a depressor substance acting upon 

 the blood-vessels; that the substance is soluble in alcohol, in which the 

 pressor substance is insoluble ; and that it is not identical with cholin, which 

 has a similar action, and might be supposed to have been extracted from the 

 nervous tissue of the lobe. These facts have now been corroborated by 

 many experimentalists, and it has recently been shown that they hold 

 good for extracts of the human pituitary (Halliburton, Candler, and Sikes, 

 1909). 



But the action upon the circulatory organs does not exhaust the effects of 

 such extracts. For in the course of certain experiments which Dr. E. Magnus 

 and I were conducting in the summer of 1901, we incidentally noticed, as one 

 of the results of intravenous injection, a marked increase in the flow of urine 

 from the ureters. Pursuing the subject further, in association with Herring 

 (1906), the fact became evident that the aqueous extract of the posterior lobe 

 — including the pars intermedia, which comes away with it when it is 



