446 



Prof. E. A. Schafer. 



[July 22 ; 



pars nervosa, and many of the islets are hollow, forming small vesicles 

 which are occupied by a " colloid " material. The inter-epithelial tissue is 

 far less vascular than that of the pars anterior. But this tissue also 

 exhibits " colloid," which is contained in spaces prolonged into the pars 

 nervosa, and the same material can even be seen discharging into the pro- 

 longation of the infundibulum which enters the pars nervosa. Indeed, in 

 some animals {e.g. cat) the infundibulum extends as a hollow canal as far as 

 the pars intermedia, and this canal receives the colloid secretion of that 

 part of the gland. The pars intermedia differs, therefore, from the pars 

 anterior not only in the structure of its cells but also in the fact that its 

 secretion — which is no doubt represented by the " colloid " material — is, in 

 all probability, not taken up directly into the blood but is passed into the 

 infundibulum and thus into the third ventricle. 



The discovery of this difference, which must be regarded as a fact of 

 great importance in the physiology of the pituitary, is due to the investi- 

 gations of Herring (1908), who has further found that the amount of such 

 colloid which is discharged into the infundibulum is greatly increased after 

 removal of the thyroid in animals. It is true that an increase in the 

 amount of " colloid " in the pituitary body had previously been noted after 

 thyroidectomy ; but this " colloid " was located by previous observers in the 

 anterior lobe, and was supposed to pass into the blood-vessels, whereas it 

 has been shown by Herring to be a product of the cells of the pars intermedia 

 and to pass into the infundibulum and third ventricle. 



Functions. 



The first investigations of a strictly physiological character which were 

 instituted to determine whether the pituitary body possesses any active 

 function were those of Oliver and myself (1895). We found that aqueous 

 or saline extracts — which may be boiled without losing their activity — 

 produce, when injected into the blood-vessels, a rise of blood-pressure which 

 is comparable to that produced by similar extracts of the suprarenal capsules. 

 We further showed that this effect is produced by an action upon the 

 peripheral arteries, which are caused strongly to contract, in this also 

 resembling the action of the active principle obtained from the suprarenals ; 

 but far more prolonged, and not due to the presence of that substance in 

 the extract. We did not in these experiments obtain any marked effect 

 upon the rate of the heart's beat, an acceleration of which is a characteristic 

 feature of the action of suprarenal extract, after the vagi have been cut or 

 paralysed (prior to which there may be some inhibition). Nor did we 



