XII. B, 4 Ruth and Gibson: House Lizards 187 



unable to say, though everything points toward "adrenin," as 

 Redfield has previously indicated. Adrenalin has a definite 

 action on the pigment of the melanophore in both the in vitro 

 and in vivo experiments; there results a gradual fading of the 

 pigment from the periphery toward the center of the cells. 



CONCLUSIONS 



1. The melanophore of Philippine house lizards {Cosmybottts 

 'platurus, Peropus mutilatus, Hemidactylus frenatus, and 

 Hemidactylus luzonensis) is a definitely fixed stellate cell, which 

 neither contracts nor expands; all pseudopods remain in situ 

 during the fading and repigmentation processes. 



2. No migration of the pigmented or farblose granules was 

 ever observed either from the center toward the periphery of 

 the cell or vice versa. 



3. The pigment in the melanophore of the Philippine house 

 lizards is actually dispersed and disappears from the granule on 

 the application of adrenalin both in vitro and in vivo, leaving 

 a definite farblose granule which can be seen with high magnifi- 

 cation. The same farblose granules are also seen in the mela- 

 nophores of the lizard bleached by white surroundings. 



4. It may be assumed that the disappearance of the pigment 

 of the granules is an intracellular chemical change, which seems 

 to occur when the melanophore is stimulated by a hormone 

 (probably adrenin) ; the pigmented state is the normal condition, 

 the melanophore in vivo elaborating the pigment when the reflex 

 secretion of the hormone is discontinued. 



REFERENCES 



(1) Ballowitz, E. tJber die Pigmentstromung in die Farbstoffzellen 



und die Kanalchenstriiktur des Chromatophoren-Protoplasmas. 

 Pfluger's Arch. (1914), 157, 165-210. 



(2) Eycleshymee, a. C. The development of chromatophores in Nec- 



turus. Am. Journ. Anat. (1906), 5, 309-313. 



(3) Hooker, D. Amoeboid movement in the corial melanophores of Rana. 



Am. Journ. Anat. (1914), 16, 237-250. 



(4) Idem. The roles of nucleus and cytoplasm in melanin elaboration. 



Anat. Rec. (1915), 9, 393. 



(5) Laurens, H. The reaction of the melanophores of Amblystoma 



larvae. Journ. Exp. Zool. (1915), 18, 577. 



(6) Idem. The reactions of the melanophores of Amblystoma larvae — The 



supposed influence of the pineal organ. Joui-n. Exp. Zool. (1916), 

 20, 237. 



(7) LiEBEN, S. Uber die Wirkung von Extrakten chromaffinen Gewebes 



(adrenalin) auf die Pigmentzellen. Centralbl. f. Physiol. (1906), 

 20, 108. 



