ACTIVE PRINCIPLES OF PARS NEURALIS 



internal secretion, closer examination of the experimental 

 data reveals that the evidence is unsatisfactory and still in- 

 conclusive. The most numerous experiments — those in which 

 oxytocic effects have been studied — are the least satisfactory. 

 The demonstration of vasopressor or antidiuretic effects by 

 blood or cerebrospinal fluid or by extracts of these is, by it- 

 self, suggestive, but does not prove that the effects demon- 

 strated are due to the active principles of the pars neuralis. 

 Vasopressor substance(s) which are pharmacologically differ- 

 ent from that of the pars neuralis can be extracted from both 

 the blood and the cerebrospinal fluid (Page, 1935). Finally, 

 even an antiduretic substance, differing from that of the pars 

 neuralis (destroyed by boiling), has been extracted from the 

 liver (Theobald and White, 1933). 



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