PHAKMACOLOGY OF HYPOPHYSEAL EXTRACTS 759 



effect. From the fact that Howell (1898) got an augmented pressor 

 . effect with the vagi cut and the negative findings of Bauer and Aschner 

 (1919) with regard to permeability changes of the blood-vessels one 

 might be led to the opinion that the initial mechanism stimulated was 

 neural. The fact that most of the reactions to pituitary extract are such 

 as follow sympathetic stimulation whereas the predominant effect in 

 the intestine is such as results from vagus stimulation offers an obvious 

 obstacle to the assumptions of any selective nervous stimulation. In view 

 of the present undeterminate status of the problem any decisive con- 

 clusion is unwarranted. 



That there is also a depressor substance in extracts from the posterior 

 lobe was first demonstrated by Schafer and Vincent (1899). This sub- 

 stance they were able to separate in solution from the pressor substance 

 by virtue of the fact that it is soluble in saline solution and absolute al- 

 cohol whereas the pressor substance is insoluble in absolute alcohol. This 

 observation was confirmed by Magnus and Schafer (1901-1902). Fiihner 

 (1914) in his extensive studies of preparations of pure active materials 

 from the posterior lobe was also able to obtain a mixture that caused de- 

 pressor effects when injected into experimental animals as was Claude 

 and Porak (1914). However, under ordinary conditions of preparation 

 the pressor substance is normally present in such amounts as to mask 

 the effect of any depressor compound that may or may not be also con- 

 tained in the extracts. Kleemann (1913) made a comparative study 

 of the effects on the circulation of extracts of the posterior lobes from 

 castrated, pregnant and normal animals. He found that the extracts 

 from the castrated subjects gave the same type of reaction as did those 

 from the normal animals, but that vasodilatation as well as vasoconstric- 

 tion resulted from the hypophyseal extracts from the pregnant animals. 



According to Parisot and Mathieu(c) (1920) the extracts have two 

 opposite actions according to the size of the dose used. The dynamogenic 

 doses producing positive responses are small and the effects are produced 



' under conditions that might occur in the living organism. The anti- 

 dynamic effects are those that are produced by the larger doses, ^they 

 tend to be depressor effects and are presumably not evoked in the living 



. organism. Such a suggestion is .valid on the basis of many of the data 

 at hand. Nevertheless, it is possible that the opposite effects obtained 

 not only on blood-pressure but also on renal and smooth muscle tissue 

 activity are due to differences in the previous condition of neural tone 

 of the experimental subject. This is a phase that has as yet lacked the 

 recognition it deserves but has been shown by Hatai and Hammett (1920) 

 and by Hammett (1920-21) to be an important factor in the type of re- 

 sponse elicited by various experimental procedures. 



An additional possibility lies in the evidence that is accruing to in- 

 dicate that the secretion of the anterior lobe is the precursor of alleged 



