182 The Philippine Journal of Science i9i7 



contraction, according to this theory, are brought about by pseudopodia, 

 the pigment granules being carried in the cell cytoplasm and the pigment 

 cells are therefore to be considered as amoeboid. 



In a more recent paper Spaeth (9) describes the melanophore 

 as a type of smooth muscle cell and in part concludes — 



That in the case of the melanophore there is no direct evidence at hand 

 for a loss or exchange of fluid during contraction. There is, however, a 

 visible and reversible colloidal aggregation of melanin granules following 

 a variety of physiological stimuli all of which elicit contractions in smooth 

 muscle. Similarly a number of physiological stimuli that produce a relaxa- 

 tion in smooth muscle brings about a dispersion of the invisible colloidal 

 particles. The aggregation of melanin granules within the melanophore 

 must therefore be considered a visible expression of the colloidal phenomenon 

 that occurs upon stimulation in the micro-homogeneous colloidal content 

 of smooth muscle cell. 



From the above theories and statements it is evident that 

 there is still considerable doubt as to the finer mechanism and 

 nature of the "contraction" and "expansion" of the melanophore, 

 or the aggregation and dispersion of the melanin granules within 

 the cell. Do we after all have more than one morphological type 

 of melanophore, or does some chemical reaction take place in the 

 cell with a subsequent disappearance or reappearance of the 

 pigment granules that may be interpreted as an apparent con- 

 traction or expansion of the cell? In a series of experiments 

 v/e have had occasion to study the pigment cells of Philippine 

 house lizards {Cosmybotus platurus, Peropus mutilatus, Hemi- 

 dactyVus frenntus, and HemidactyliLS luzonensis — the last very 

 rare), and we have observed that the melanophoric changes in 

 these animals are of a type that does not accord with the descrip- 

 tions given by investigators who have worked with the other 

 types of melanophores previously mentioned. 



Our experiments have been made both upon the living lizard 

 and on isolated pieces of skin that could be studied under the 

 microscope. Some of our observations, along the lines recorded 

 by other investigators, include the results of enucleation of the 

 eyes, decerebration, severing the spinal cord, various kinds of 

 stimulation, and the effects of physiologically active substances 

 such as adrenalin chloride, chloretone, curare, atropine, potas- 

 sium cyanide, ether, chloroform, carbon monoxide, and isotonic 

 salt solutions. 



The change of color in Philippine house lizards is effected 

 fairly rapidly, both from a light to a dark color and vice versa, 

 and the period of time for each change is approximately the 

 same under normal conditions. The variation in color range 

 is merely one of light and dark intensity and includes all the 



