PHARMACOLOGY OF HYPOPHYSEAL EXTRACTS 749 



While the studies just reported fail to give conclusive evidence that the 

 pars intermedia of the hypophysis is a definite source of the active prin- 

 ciples commonly attributed to the posterior lobe, they do seem to afford 

 evidence favoring the hypothesis that the substance giving rise to the 

 contraction of uterine muscle is not the same substance that causes the 

 blood-pressure changes. 



From the clinical point of view Barker and Mosenthal (1917) and 

 Barker and Hodge (1917) have been of the opinion that diabetes insipidus 

 may possibly be due to an underfunction of the pars intermedia of the 

 hypophysis cerebri rather than to hyperpituitarism. They have reported 

 successful results obtained in that disorder by the daily subcutaneous ad- 

 ministration for four days of one cubic centimeter of a pituitary prepara- 

 tion containing extracts of both the pars posterior and pars intermedia. 

 The dose was then increased, but was not rigidly followed in every case. 

 The patients were kept comfortable and excreting a normal amount of 

 urine and of normal specific gravity under this treatment. The authors, 

 however, do not stress the idea that the disorder is due to a disturbance of 

 the pars intermedia and advocate the keeping of an open mind on the 

 subject. 



Pharmacology of the Posterior Lobe, Active Principles. Isolation 

 and Properties. The reports of McCord (1915) and Fenger (1916) indi- 

 cate that the production of the active principles by the posterior lobe begins 

 at an early age, since extracts from fetal hypophyses give the characteristic 

 pressor responses when tested. The latter investigator is of the opinion 

 that the activity of the lobe is somewhat enhanced during the growing 

 period. Herring (1908) has made an extensive study of the activity of 

 extracts from the hypophysis or the posterior lobe of various types of 

 animals and his results taken in conjunction with those of Fenger (1916), 

 Lieb (1914-15) and others give proof that similarly acting substances, 

 as tested pharmacologically, are the common property of the gland as 

 found in a wide range of animals. The exact chemical nature of the active 

 principles of the posterior lobe extracts is as yet unknown. Abel and 

 Kubota (1919) were able to isolate p-iminazolylethylamin from the pos- 

 terior lobe and consider that this compound, called histamin for con- 

 venience, is the plain muscle stimulating constituent of pituitary extracts. 

 But since they were able to prove its presence in all tissues of the body 

 they admit that it is not specific to the hypophysis. They adduce as 

 evidence that histamine is the smooth muscle contracting substance of 

 posterior lobe extracts, the fact that it causes a similar type of response 

 of uterine muscle as do the extracts themselves as was earlier noted by 

 Niculescu (1914), Roth(a.) (b) (c) (1913-14) and others. There is, how- 

 ever, evidence that this compound is not a specific active principle of such 

 extracts. Although Guggenheim(a) (1912), Fuhner (1913), Cow(&) 

 (1919) and others base their primary objections to the idea of the identity 



