Vol. X] VON GELDERN—SKIN OF ANOLIS CAROLINENSIS 91 



bleaching and bits of skin may then be held between pieces of hard- 

 ened celloidin and sectioned. The solubility of the yellow sub- 

 stance forbids imbedding in either celloidin or paraffin. These 

 sections should then be mounted in glycerine. 



For examination of the cellular elements, tissues imbedded in 

 both celloidin and paraffin were sectioned at 1 5 microns and stained 

 with haematoxylin and eosin. Frozen sections treated with gold 

 chloride for the purpose of showing the nerve endings have, so far, 

 not been successful. 



In order that the histological picture be made as complete as 

 possible, the elements of a single lateral scale will be described 

 (Figs. 10, II, 12, 13 and 14). Where differences exist in the scales 

 of other parts of the skin these will be mentioned. The layers 

 comprising the scale will be taken up in their order, beginning 

 from without inward. 



Epidermis. — The outermost, transparent layer or epidermis 

 may be divided into an outer, horny layer or stratum comeum 

 and an inner, stratum germinativum. The epidermis is consider- 

 ably thicker near the siunmit of the scale than at the periphery 

 where it becomes continuous with the thin epidermis of the space 

 between the scales. 



The stratum corneum may usually be divided into two layers, 

 an outer one which is separated by an interspace from an inner. 

 This outer layer represents that portion which is ready to be cast 

 off in moulting (Figs. 8 and 12). The inner layer does not stain 

 with eosin, being straw-colored. The squamous cells may show 

 clear, non-staining, round bodies, representing the degenerated 

 nuclei. The layer undergoes marked keratinization at the apex of 

 the scale with the formation of a homogeneous, homy ridge or keel. 

 This thickening is more marked in the scales on the ventral aspect 

 and those along the mid-dorsal line. Keratinization of the other 

 cells of the stratum comeiun, other than in the keel, is not so 

 marked and, due to the dehydrating effect of the air, become fairly 

 well separated so that their outlines may be distinguished (Fig. 8). 



Briicke has described "interference cells" in the outer layer of 

 the stratimi corneum in Chamcsleon vulgaris. These cells, he be- 

 lieves, modify the color of the skin by reflected light to a very 

 marked extent. 



Keller believes that the outer cells of the outer layer of the 

 stratum comeum contain minute closely placed columns arranged 

 at right angles to the surface of the cell. He calls this outer layer 



