THE APPARATUS OF SMELL. 815 



nerve-tubes on one side, and on the other are furnished, for the most part, 

 with rods which attain the free surface of the tongue. The superficial, or 

 protective cells , completely envelop the preceding; they are a kind of 

 epithelial-cells imbricated like the skins of an onion. 



These sensitive organs are very numerous in the walls of the calyciform 

 papillae. Schwalbe reckoned their number at 35,000 in the papillae of the 

 Ox. They are not met with in these papillae only; Lowen has found 

 them in a large quantity of fungiform papillae, if not in all. There is 

 nothing extraordinary in this, as the whole surface of the tongue may, in 

 various degrees, appreciate savours. (Szabadfoldy has described small 

 oval or pyriform bodies, lying with their long diameter parallel to the surface. 

 The axis-cylinders of the gustatory nerves enter these, and terminate at their 

 lower part in a slight swelling ; so that they resemble small Paccinian 

 bodies). 



DIFFERENTIAL CHARACTERS IN THE APPARATUS OF TA8TE IN OTHER THAN SOLIPED 



ANIMALS. 



In the domestic raammifers, the differences in this apparatus are found in the number 

 and variety of forms of the papillae of the tongue. 



In Ruminants, the calyciform papillae are disposed in two rows at the base of the 

 tongue; they are smaller than in the Horse, but more numerous about a dozen being 

 counted in each row. In the Ox. the filiform papillae are covered by a horny sheath, 

 which renders them hard to the touch. 



The Pig, like Solipeds, has only two calyciform papilla?. 



In the Dog and Cat, there are two principal papillae, and in their vicinity some smaller 

 calyces. The filiform papillae are composite, and covered by a thick horny layer. 

 Between them, regularly placed, are seen the fungiform papillae, which have a brilliant 

 aspect when looked at obliquely to the surface of the tongue. 



COMPARISON OF THE APPARATUS OF TASTE IN MAN \VITH THAT OF ANIMALS. 



This has been already alluded to at page 364. 



CHAPTEE III. 



APPAKATUS OF SMELL. 



THE sense of smell gives the appreciation of odorous emanations to animals. 

 The active instruments of this sense are the filaments of the first pair of 

 encephalic nerves, which ramify in the upper part of the pituitary membrane ; 

 this becomes, with the cavities it lines, the olfactory apparatus. These parts 

 have been already referred to at page 444. 



(The olfactory filaments, passing down from the olfactory ganglion, form 

 a plexus upon the surface of the pituitary membrane. These filaments, as 

 already noted, differ widely from those of the ordinary cephalic nerves, in 

 containing no white substance of Schwann, but are nucleated and finely- 

 granular in structure, and resemble greatly the gelatinous form of nerve- 

 fibres. Their distribution ig limited to the membrane at the upper third of 

 the nasal septum, the upper part of the turbinated bones, and the wall of 

 the nasal cavities adjoning the cribriform plate of the ethmoid bone : all 

 this surface being covered with an epithelium of a rich sepia-brown hue. 

 As has also been mentioned, Schultze divides these cells into two sets: 



