PARS INTERMEDIA AND PARS TUBERALIS 



Glogner (1933) who used N/io NaOH. Dietel (1934) puri- 

 fied his extract further by precipitation with acetone and by- 

 dissolving the active principle, precipitated by acetone, in 

 boiling absolute alcohol. The alcoholic extract, after the re- 

 moval of the solvent, was dissolved in water. The potency 

 of the extract was high (i "Phoxinus-umt," 0.2 y = 0.0002 mg. ; 

 1 "frog-unit," 0.0003 '>')• Zondek and Krohn (1932) recom- 

 mended that 0.25 per cent acetic acid be used for the initial 

 extraction of the erythrosome-dispersing substance. 



It has been reported that blood may "activate" the 

 chromatophore-affecting principle contained in a pituitary 

 extract (Popa and Fielding, 1933; Jores and Will, 1934). 



Solutions of the chromatophore-dispersing principle(s) can 

 be prepared free from protein; the Pauli reaction is negative. 

 The hormone readily withstands boiling even in a solution 

 containing N/io NaOH (see pp. 315-16). The hormone is 

 quite soluble in various concentrations of ethyl alcohol includ- 

 ing hot absolute alcohol; it is insoluble in ether and acetone, 

 and only slightly soluble in butyl alcohol and chloroform. 

 Dietel (1933) considered that it was not an easily adsorbed 

 substance (see also Houssay and Ungar, 1924, and Jores and 

 Velde, 1933). 



Several investigators have confirmed the observation of 

 Hogben and Winton (1922) that the chromatosome-dispers- 

 ing hormone(s) is destroyed by tryptic but not by peptic 

 digestion. Light and particularly ultraviolet radiation are 

 said to inactivate the hormone especially if it is exposed 

 when in an acid solution (Dietel, 1932; Jores, 1932; Zondek 

 and Krohn, 1932). Although the chromatosome-dispersing 

 hormone(s) has sometimes been identified with the pressor 

 principle (but less frequently with the oxytocic principle) 

 of the pars neuralis, its distribution, its physico-chemical 

 characteristics (solubility, ultrafiltration, etc.), and its sur- 

 vival in alkaline solution even after boiling have all served 

 to demonstrate that it is not identical with either the vaso- 



[317] 



