MELANOPHORES OF THE HORNED TOAD 



299 



to the epididymis and that a small portion of adrenal tissue may 

 readily have been incorporated in the extract. 



When extracts made from the adrenal glands of the horned 

 toad are injected under the skin of living specimens of this Uzard, 

 a contraction of the melanophore pigment is produced. Extracts 

 of liver, of skeletal muscle, and of testis do not cause any con- 

 traction of the pigment. Extracts of the epididymis produce 

 a contraction of the melanophore pigment of horned toads into 

 which they are injected, but, as pointed out, these extracts have 

 been shown to contain adrenin. 



Fig. E Record of the effect. of an extract of the liver of the horned toad (intro- 

 duced at X) upon the rhythmic contractions of the intestine of the rat. At Y 

 Ringer's solution replaced the extract. 



Fig. F Record of the effect of an extract of the skeletal muscle of the horned 

 toad (introduced at X) upon the rhythmic contractions of the intestine of the 

 rat. At Y Ringer's solution replaced the extract. 



Fig. G Record of the effect of an extract of the testis of the horned toad 

 (introduced at X) upon the rhythmic contractions of the intestine of the rat. 

 At Y Ringer's solution replaced the extract. 



From the foregoing it appears that the adrenal glands of 

 the horned toad contain a substance, adrenin, which is capable 

 of producing a contraction of the melanophore pigment of this 

 animal. The question is thus raised: can the adrenal glands, 



