Vol. X] VON GELDERN—SKIN OF ANOLIS CAROLINENSIS 109 



observations over long periods of time of the habits and color 

 states of these lizards in their natural environment. The first 

 method of attack is always open to criticism so long as the experi- 

 ments are not carefully controlled; for instance in none of the 

 experiments performed by either Parker and Starratt or Carlton 

 were the factors of varying external stimuli taken into con- 

 sideration. 



Lizards kept for long periods in confinement may give one set 

 of results but one is not justified in drawing any general con- 

 clusions as to the behavior of all lizards. 



I wish to thank Doctor Hardesty and Doctor Garey for their 

 helpful suggestions. 



Summary 



1. In its color changes, Anolis carolinensis shows a greater 

 variety of colors than has been usually described for this animal. 

 It may at times take on other colors than the emerald green, 

 mahogany brown, and the variations intermediate between these. 

 The variations, though apparently less frequent, correspond 

 fairly 'closely with the variations described for Chamceleon vulgaris. 



2. The color changes, in addition to general variations in Anolis 

 carolinensis, as observed in its natural environment especially, 

 seem to be induced by variations in external stimuli. Rhythmic 

 changes of color may be observed with the animal in the same 

 position with unchanged temperature ^d light, and emotional 

 states interpreted as fear, sexual excitement, and anger (prelim- 

 inary to and during combat) seem to more actively bring 

 about color changes than temperature and light. Color changes 

 in sympathy with environment (protective coloration) seem 

 probable. 



3. In structure, the skin of Anolis resembles that described 

 by other investigators for Chamosleon vulgaris, except no "Negative 

 Relief Schicht" could be distinguished in the stratum corneum of 

 the epidermis, and no cells corresponding exactly to the eryth- 

 rophores of Pouch et could be determined. Also the oil droplet 

 layer described here for Anolis is not the same as the ochrophore 

 layer described by Keller for Chameleon. 



4. The observations of Carlton that the processes of the mel- 

 anophores in Anolis are fixed or non-amceboid and that migration 

 of the pigment granules occurs within them, is hereby confirmed. 

 In this the nielanophores are similar to those described for 



