MORROW — NOTES ON THE CARIBOU. 297 



"The microscopic examination of this organ proved it to be of 

 Epidermic origin. Sections through the thickness of its walls 

 showed an external layer of flattened prismoidal cells with small 

 nuclei, a deeper or internal layer in which the cells were more 

 rounded and filled with granular protoplasm, (this difference in the 

 uppermost and lowermost layer was brought out by the staining 

 process, and it is in these only that we find the line of demarcation, 

 the intervening layers merging gradually one into the other). 

 Other structures observed were the hairs and hair follicles with 

 their accompanying tissues, and some fibres representing, no doubt, 

 the true skin, which is not developed in these organs to any con- 

 siderable extent. The two layers of cells correspond to the same 

 parts in man, viz., a horny layer external, but of course internal in 

 the ' cul-de-scac ;' a mucous layer external when the sac is dissect- 

 ed from its surroundings, the changed position of these layers is 

 owing to the circumstance of the sac's being an invagination of the 

 epidermic layer into the true skin. 



" Regarding the function of this structure, various and contra- 

 dictory opinions are expressed, that of its being glandular being 

 most prevalent ; again it is said to have no existence in the Wapiti and 

 Moose, and fore feet of the adult Caribou. The fact of its existence 

 in fore and hind feet of the Virginia Deer being well understood, 

 its presence in this animal is said to be for the purpose of leaving 

 a trace or scent on the ground, and in this way serving the union 

 of the sexes at certain seasons, but if this is the case, we may 

 ask why should it not exist in the Wapiti and be fully developed 

 in the Caribou and Moose, since it must be obvious to us that the 

 fulfilment of the conditions which obtain in the Virginia Deer are 

 required also in the Wapiti ; more than this, we know that a true 

 scent organ in the Caribou is situated on the inside of the heels or 

 gambrils. 



' ' I may say here that on the occasion of my first dissection of 

 the organ in the Caribou buck fawn, I expressed the opinion, that 

 this organ or structure would be found also in the fore feet of the 

 adult animal, though perhaps more rudimentary; a subsequent 

 examination of the fore feet in an adult doe confirmed this opinion 



