THE PITUITARY 357 



a priori that it would be more likely to furnish active physio- 

 logical substances. 



But we must remember that there are epithelial elements 

 in, and in close relation to, the nervous portion (Figs. 94 and 

 95), and it was a natural assumption that these, and not the 

 nervous portion proper, would be found to yield the pressor 

 substance. But some years ago, Professor Osborne and myself 

 tested the matter, and found that an extract made from the 

 central part of the infundibular portion devoid of epithelial 

 elements is much more active than one from the peripheral 

 epithelial part. We expressed the opinion that probably the 

 external layer would be found to be inactive if it could be 

 obtained quite free from admixture with the central portion. 



Schafer and Herring found this to be the case too with the 

 substance which acts as a diuretic. Improbable, then, as it 

 would appear at first sight, the conclusion is inevitable that it 

 is the nervous portion proper which contains the substance 

 or substances having such pronounced pharmaco-dynamical 

 properties, different from those possessed by other kinds of 

 nervous tissue. 



I have never had an opportunity of repeating the experi- 

 ments carried out in conjunction with Professor Osborne, but, 

 since they have been amply confirmed, I am strongly inclined 

 to adopt the view of Houssay that the substance or substances 

 are secreted by the cells of the pars intermedia, and then collected 

 and concentrated, or changed into more active forms in the nervous 

 portion proper. 1 



No physiologically active substances can be extracted from 

 the anterior lobe (except a depressor substance, which is 

 common to all organs and tissues). This part of the pituitary 

 is related to the general growth of the body, and especially of 

 the skeleton. (See Section F.) 



F. Feeding and Metabolism Experiments 



The first metabolism experiments were performed by Schiff. 



1 Herring has recently confirmed the results of Osborne and Vincent. 

 " The pars nervosa is from two to five times more powerful than the pars 

 intermedia in its action." He thinks that the substance acting upon the 

 uterus is formed at an early stage in the pars intermedia, but the substance 

 acting upon the blood-pressure and kidney is a later product, resulting from 

 the breaking down of the hyaline bodies or disintegrating pars intermedia 

 cells in the pars nervosa. 



