420 APPENDIX. 



accompany the hair follicles or bulbs over the whole integument of the ani- 

 mal, " this exception is made for obvious anatomical reasons," nevertheless 

 the sebaceous follicles were not observed in the specimens examined with the 

 microscope. 



4th. The examination of the matter filling the tubes in the Virginia deer, 

 and present in much smaller proportion in the Caribou, showed it to consist in 

 principal part of desquamated epidermic scales and oil globules. Microscopi- 

 cally it resembled smegma from the skin of man, or perhaps closer still, the 

 " vernix caseosa " from that of a recently delivered infant ; remembering that 

 the epidermis in man and in all animals is a non-vascular tissue, that, unlike 

 our other tissue, it is shelled off from the surface, we can readily account for 

 these desquamated scales being retained here in a narrow pocket, from which 

 they could not be easily discharged. Retrograde changes in these cells, secre- 

 tions from sebaceous and sweat glands in adjacent parts, will account not only 

 for the oily matter seen, the viscidity of the substance, but also for the odor 

 which it possesses, the latter being no greater than that of the general integu- 

 ment, and arises from the same cause, namely, the perspiration ; but in this 

 respect they are not in any degree comparable with the glandular collection at 

 the hocks before mentioned, which will retain the peculiar odor of the animal 

 for a long ijeriod after the removal of the skin. 



In presence of these facts we must conclude that this organ is only rudi- 

 mentary, having no function which is obvious to us; it is not a secreting organ, 

 since it lacks glandular tissue; the opening in the dorsum instead of the sole 

 of the foot, would point also in this way ; it does not serve to give strength or 

 firmness to the foot, having none of the toughness and elasticity of the skin 

 in other parts, without comparison with the tendons, etc., which are pi'ovided 

 for this purpose (some instances of organs without uses were also given). 

 Fi'om an individual point of view, taking in all the circumstances referred to, 

 there appear to be only two ways of accounting for this structure ; it is either 

 an aborted " ungual follicle," or otherwise it is a cul- de-sac, representing the 

 suture formed by coalescence of the skin fi-om side to side in the foetus. Its 

 structure would convince one of the first conclusion if the animal had rudi- 

 mentary toe bones in the same position, indicative of a three-toed ancestor ; 

 but all observations relative to the morphology of the foot are opposed to this 

 view, since the outer bones and their appendages are aborted in all animals of 

 this kind; we are therefoi'e compelled to adopt the other view, which can only 

 be settled satisfactorily by examination of the part in the foetus. Nevertheless, 

 knowing the difficulty of substantiating any theory connected with its supposed 

 origin and use, still more the difficulty of ridding one's mind of a theory once 

 entertained, my faith in either of these is held very loosely. 



The paper concluded with some general observations by Mr. Morrow, and a 

 conversation in which a number of the members of the Institute took jjart. 



