COLOR CHANGES IN SKIN OF LIZARD. 453 



The microscopical structure of the skin in the lighter parts of 

 the dorsal region of Ptychozoon differs in some respect- with that 

 in the dark -tripe-. In the light-gray parts (1 . - the epidermis 



^^ 



* 



^> <fcW $ 



: J^^ ^ -. - - iL * 



x 



^r' 



I- 1-. /' ' Italum, newly-hatched specimen. Longitudinal 



olored portion of the dorsal region. 11 \\lin- 



c, cutis with chromatophores; t, cell-layer :mis; 



MIS. which has loosened from the parts umli-riu-atli it; 



contain- no ; ,t at all, the large pigment-cells con>i-t of a 



l,n\:( boily \\hich is situated in the cutis and a number of rami- 



;ioii- \\hich are directed towards the epidermis and terminate 



immediately underneath the latter. In the living state a nearly 



continuous la\er of black pigment is distributed under the 



epiilermi- b\ t!ie contraction of the chromatophores. \Yhcn the 



and again, the pigment flows back to the deeper 



la\er ..i the ititis and the color of the animal becomes much 



(T. 



In the dark stripes (Kig. 6) the chromatophores of the cnti- 

 are u-nall\ of a somewhat smaller size than those of the lighter 

 parts of thel y, the whole amount of cutis-pigment in a certain 



'. ^r-* 



^rv 



FlG. 6. /'' 'i homalocephalnm. Longitudinal sc-> of 



tin- the dorsal region of the specimen of Fij;- 5. II;i-m,itxylin- 



in. X 100. c, cutis with chromatophores; t. cell-layer of c-j 

 with cpiili-rriiis-piiiiiii-iit ; A. horn-layer of epidermis; m. n 



On, ho\\e\er. i- about the same. Be:-ide> the eutis-pi^nu-nt 

 an epidermis-pigment is also present here. The uppermo>t parts 

 ot the celU of the e]ulermis are crowded with small black pig- 

 ment granule^ \\hirh are found immediately underneath the 

 30 



