100 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



distribution of the pigment. The number varies not only in 

 melanophores in the same scale, but also melanophores of one 

 scale may contain more pigment than those of another. Also the 

 intensity of the color of the pigment may vary, individual or 

 groups of melanophores containing a lighter brown pigment than 

 others. This appears to be irrespective of the number of granules. 

 These differences in amount and intensity in color are so striking 

 that there is no doubt as to their occurrence (Figs. 11,12 and 13). 



In the green state of the skin of Anolis (Figs. 10 and 11) the pig- 

 ment granules are present only in the bodies and proximal parts 

 of the primar3^ branches of the melanophores. This proximal 

 migration of the pigment is practically complete and the finer 

 distal branches are clear and transparent. In some of these finer 

 branches, however, a few scattered pigment granules may have 

 failed to follow the mass of pigment and their presence allows one 

 to detect more readily the finer branches. The bodies of the melan- 

 ophores during the proximal migration of the pigment are neces- 

 sarily darker than after distal migration. In proximal migration 

 of the pigment it is noticed in the primary branches of the melano- 

 phores that there is an area of gradation between the dense pig- 

 ment on one side and the clear part on the other side where the 

 pigment is much less dense. In this portion the pigment granules 

 apparently arrange themselves in parallel rows (Figs. 11 and 15). 

 This parallel arrangement has also been observed by Keller in the 

 chameleon. 



In the brown state (Figs. 12 and 13) the finest branches lying 

 immediately beneath the epidermis are filled with closely packed 

 pigment. This gives the appearance of a thin, dark-brown layer 

 lying just beneath the epidermis in vertical section. One might 

 conclude that, in order that this appearance can be produced, the 

 terminal branches must anastom.ose and fonn a plexus. That this 

 is not the case, however, may be readily determined in tangentially 

 cut sections where the terminal branches appear as separated but 

 closely packed, dark-brown dots (Fig. 14). Keller makes this 

 observation for the chameleon and Carlton for Anolis. 



It is probable that the green state of Anolis does not represent 

 the maximimi degree of proximal migration of the pigment. In 

 certain scales, pigment may be absent even in the primary branches 

 and be confined entirely to the cell body which appears like a dark 

 brown or black sphere. Furthemiore the pigment may be con- 

 densed to such a degree that a clear broad halo of cytoplasm may 



