willard: cranial nerves of anolis carolinensis. 2& 



between Figures A and C. An exception should possibly be made to 

 the statement of their universal distribution, for they are apparently 

 absent from that part of the digit which is provided wuth adhesive 

 organs, "suckers," but they appear again on the small terminal part 

 of the digit, where the bristle projects well beyond the imbricated 

 margin of the scales (Figure D). 



The structure of this tactile organ is described here only in so far as 

 it was shown in the material prepared for general study. The fixation 

 in Vom Rath's fluid is of course excellent, but it precludes varied stain- 

 ing methods, and certain differences that might thus have been brought 

 out have not been observed. In section these organs are very incon- 

 spicuous, and if they did not interrupt slightly the free and basal 

 margins of the epidermal layer, they would escape notice in the un- 

 stained osmic-fixed sections. In nearly all regions the corneous layer 

 of the skin is slightly parted from the underlying epidermis and the 

 abrupt thinning of this layer where it covers the tactile spot is more 

 conspicuous than the organ itself. The modification in the horny 

 layer, aside from the bristle, is effected more by the projection of the 

 sense bud into this layer than by a depression of the circular area 

 covering the bud. The cuticular bristle projects from the center of 

 this circular area. It is slightly tapering, ending in a fine point. No 

 structure could be recognized within this, nor any indication of how 

 it is produced. The full length of these structures is not often pre- 

 served in sections. Those found in sections measure up to 20 micra. 

 in length. The surface view shows them somewhat longer; however, 

 the text figures do not represent them with accuracy on this point. 

 The structure of the organ itself agrees closely with that of Coronella 

 (Maurer, '95), with this difference, however, that the column of cells 

 forming the tactile end organ (/) could not be identified as a definite 

 and separate structure. The continuity of the basal layer of the 

 epidermal cells is interrupted by a ball of very small cells with rounded 

 nuclei forming a bud which projects beyond the limits of the other 

 cells and this approaches nearer to the free surface of the horny layer. 

 Should the corneum be stripped off in Coronella (see Maurer), the tac- 

 tile spots would appear in it as in Anolis. Despite the fact that all the 

 other published figures show it, the innervation was not determined in 

 Anolis beyond the fact that medullated fibers are often found directed 

 through the corium toward the organ. Pieces of integument w^ere 

 stripped off in the fresh condition, stretched out, and stained with 

 osmic acid, but with no more definite results. The skin is seen to be 

 richly supplied with medullated nerve fibers, but their distribution 



