ORGANS OF THE SENSES. 503 



in the accuracy of much of the description of it given above, 

 the author fully concurs. He does not, however, hesitate to 

 affirm that no glands at all analogous to sweat-glands exist 

 in it ; the membrane of this region is indeed thickly studded 

 with mucous follicles, apparently in no respect dissimilar to 

 those of the pituatory region, except that they are smaller in 

 size, and more delicate in structure. 



The chief characteristics of the olfactory region consist, 

 then, in its glandular epithelium, in the presence of pigment 

 cells lying beneath this, in its more delicate structure, in the 

 presence of gelatinous nerve filaments, and in a somewhat 

 different arrangement of the blood-vessels. (See Plate LXIX. 



fig- !) 



In the sheep this region is rendered almost black by the 

 presence of very many pigment cells which are of the stellate 

 form. 



Mr. Quekett pointed out, some years ago, the very curious 

 fact that the blood-vessels of the olfactory region of the 

 human foetus, and that of mammalia in general, are disposed 

 in loops, the convexity of each of these presenting a decided 

 dilatation. (See Plate LXIX./^. 12.) 



Much interest is attached to the existence of these loops, 

 since they appear to indicate the presence of true papillae in 

 the seat of smell of the mammalian foetus ; if such be the 

 case, however, it is very certain that neither the papillae nor 

 loops exist in the olfactory region in the adult condition of 

 the nasal organ. 



The most rigorous search has failed to detect the presence 

 in the olfactory region of cells, which could be decidedly pro- 

 nounced to be nervous or ganglionic. 



The nerves of the nose are the first pair, branches of the 

 fifth, and motor filaments from the seventh pair. The first 

 pair are, doubtless, the proper nerves of smell, while the fifth 

 gives common sensibility to the nose. 



The olfactory lobes are prolongations of the white or 

 fibrous portion of the brain, and consist, like it, of slender 

 tubular nerve filaments, intermixed with the delicate trans- 

 parent cells, described in a previous division of this work. 



