748 FEEDEEICK S. HAMMETT 



exerted a contractor or oxytocic effect on the virgin rat uterus. He at- 

 tributes this to the possibility of a greater sensitivity of the uterus to any 

 potent extract since "the contraction of uterine muscle is a simple matter 

 compared with the variety of factors which are concerned in the general 

 rise of blood-pressure, and it well may be that a vastly greater amount of 

 the active principle is necessary to produce a rise of blood-pressure than 

 will suffice to bring about contraction of the uterus. It may be, too, that 

 the active material exercises a selective effect upon uterine muscle." Nev- 

 ertheless, since Schafer and MacKenzie (1911) have shown that extracts 

 of the pars intermedia may act as galactagogues there is a possibility that 

 the active principle that produces this and the oxytoeic effect is different 

 from that concerned in the rise in blood-pressure, increased volume of 

 the kidney and diuresis, and is a constituent of the pars intermedia. 

 Herring (1914) also found that extracts of the pars intermedia did not 

 cause expansion of the kidney nor diuresis while they did tend to stimulate 

 a slight milk secretion. He then makes the assumption that the active 

 principles, presumably of the posterior lobe, have their origin in the cells 

 of the pars intermedia, the epithelial cells of which secrete a thin colloid 

 material which finds its way into the pars nervosa and is there stored as a 

 hyaline material. 



Herring (1914) extended his observations upon the activity of the 

 extracts of the pars intermedia to a quantitative comparison of equivalent 

 extracts from this portion and the pars nervosa of the hypophysis. He 

 found that the pars intermedia contained but from one-half to one-fifth the 

 amount of uterine contracting substance obtaining in the posterior lobe 

 and confirmed his previous results on the inability of extracts of the pars 

 intermedia to cause an increase of kidney volume, diuresis or rise in blood- 

 pressure. As far as the kidney effect is concerned, Motzfeldt(a) (&) 

 (1917) has reported that the effects of oral administration of pars inter- 

 media indicate the possession of an antidiuretic action. Shamoff (1915- 

 10) did not obtain any reaction with pars intermedia when using intestinal 

 segments as the test object. 



From these experiments it would appear as if the pars intermedia of 

 the hypophysis does contain a substance or substances capable of causing 

 contraction of the isolated virgin uterus and stimulating mammary secre- 

 tion. Such an oxytocic principle was shown by Schmidt and May (1917) 

 to result from the barium hydroxid hydrolysis of tethelin and it has been 

 proven that extracts of the posterior lobe of the hypophysis exert a similar 

 action. 



It would appear as if a uterine-contracting principle is in some form 

 or other a constituent of all parts of the hypophysis. Since Abel and 

 Kubota (1919) have found that histamin, a uterus-contracting substance, 

 is present in practically all tissues of the body, perhaps this is the cause 

 of the reaction from extracts of the pars intermedia. 



