746 FKEDEKICK S. HAMMETT 



the fact that when he himself prepared an extract by their method he too 

 failed to obtain a depressor effect. Hence, it is evident that extracts of 

 the anterior lobe as ordinarily prepared and given in moderate doses have 

 little if any action on blood-pressure, though Motzfeldt (1917) claims to 

 have obtained an antidiuretic action as a result of its administration. ~No 

 physiological action on the intestine could be obtained by Shamoff (1916- 

 17) in her studies of these extracts. 



On account of the probable presence of an iminazolyl group in tethelin 

 Kobertson (1916) was inclined to believe that the compound is related to 

 the physiologically active substances of the posterior lobe of the pituitary 

 body, which too is supposed to contain this grouping. Although tethelin 

 as isolated does not cause the characteristic responses in blood-pressure and 

 diuresis that are obtained by posterior lobe extracts, when Schmidt and 

 May (1917) hydrolyzed the compound by barium hydroxid the resultant 

 solution was found uniformly to cause contraction of the isolated uterus 

 of the virgin guinea-pig, and a slight rise in the blood-pressure of rabbits. 

 These authors, therefore, consider that the active substance of the posterior 

 lobe of the pituitary body is largely derived from a splitting of a substance 

 which is a product of the secretion of the anterior lobe and which contains 

 an iminazolyl radical, inferentially considering tethelin as this precursor. 



Pharmacology of the Pars Tuberalis. Before going on to a consid- 

 eration of the pars intermedia of the hypophysis, it is necessary to give a 

 brief description of the studies of the pars tuberalis of the hypophysis 

 first histologically described by Tilney(&) (1913). This structure is ap- 

 parently a constant component of the hypophysis distinct from the pars 

 anterior, pars intermedia and pars posterior and consists of an epithelial 

 investiture of the neural stalk having a distinct embryological origin, as 

 shown by Atwell (1918) in the rabbit. Investigations of the possible 

 pharmacodynamic activity of this portion of the hypophysis were under- 

 taken by Atwell and Marinus (1918), because both anterior lobe and 

 posterior lobe preparations are frequently contaminated by its inclusion. 

 These authors separated the pars tuberalis from the other parts of the 

 hypophysis, but were unable to obtain any evidence of the presence of an 

 oxytocic or prcssor principle in sufficient amounts to justify the assump- 

 tion that this cellular group is a physiologically functional part of the 

 posterior lobe. In a series of experiments conducted by Marinus (1919) 

 in which the effects on growth of the anterior lobe and the pars tuberalis 

 were studied no alterations were observed in the animals having had the 

 latter substance administered to them, from which he came to the conclu- 

 sion that no anterior lobe functions can be attributed to the pars tuberalis. 



These brief studies would lead to the opinion that this histologically 

 and embryologically distinct part of the hypophysis takes no part in the 

 functions of the other portions of the gland as exhibited by the pharmaco- 

 logical activity of their extracts, 



