THE PITUITARY BODY 



means of "acid" whereas "activation" of the melanosome- 

 dispersing hormone is effected by means of "alkaH." They 

 also observed that, if solutions at an alkaline pH were boiled, 

 the potency of a melanosome-dispersing hormone was in- 

 creased whereas that of an erythrosome-dispersing hormone 

 was diminished. The "erythrophore-hormone," but not the 

 "melanophore-hormone," is readily soluble in absolute ethyl 

 alcohol (however others, including Jores, have reported that 

 the "melanophore-hormone" is soluble in absolute alcohol). 

 They believed that the erythrosome-dispersing hormone is 

 secreted by the pars intermedia and that the melanosome- 

 dispersing hormone is secreted by the basophils of the pars 

 glandularis. 



Rodewald's observation (1935) should also be mentioned. 

 She found that the pituitary of frogs kept in the dark caused 

 practically no melanosome dispersion in the frog, but still 

 caused erythrosome dispersion in Phoxinus. 



The preparation of extracts producing changes in the chro- 

 matophores; the chemical properties of such extracts. — Prior to 

 1930, the extraction of the melanosome-dispersing hormone 

 had commonly been accomplished by boiling the tissue (e.g., 

 acetone-desiccated posterior lobe) for a few minutes in a 

 dilute (0.25 per cent) solution of acetic acid. In 1930, how- 

 ever, Hogben and Gordon showed that the addition of NaOH 

 (final concentration 1.35 N) to an extract of the pars neuralis 

 abolished the pressor effect of the extract but increased the 

 extract's melanosome-dispersing effect. Hogben and Gordon 

 believed that, by its local vasoconstricting action, the vaso- 

 pressor hormone had lessened the melanosome-dispersing 

 effect of the extract. Recent work of others, however, has 

 led to the conclusion that extraction in an alkaline medium 

 "activates" or liberates more of the hormone affecting the 

 melanophores. Methods employing an alkaline extraction- 

 medium initially have been described by Dietel (1933-34) 

 who used a saturated solution of Ba(OH), and by Jores and 



[316I 



