282 
On the Teeth of the Ox, Sheep, and Pig, 
explained liereaftei- when the subject of dentition is considered. 
It may be here added, however, that the incisors are the same in 
number, whether we regard the temporary, or milk set as it is 
sometimes called, or the permanent which succeed them. 
Connected with the collection of the food we also see further 
evidence of design in the arrangement of the parts which are more 
or less employed in the act. Various plants are known not only 
to differ with reference to the quantity of their nutrient matters, 
but to possess properties which are prejudicial to animal life. 
Such plants as these are, as a rule, instinctively avoided. In the 
springing up, however, of these noxious plants with a luxuriant 
herbage, an animal cannot always avoid receiving them with the 
morsel. Essentially it is the office of the sense of taste to cause 
the ejection of such matters from the mouth, that they may not 
enter the system and exert their baneful influences. 
Substances, however, vary considerably in the impressions 
they produce on the sense of taste, some being nearly insipid, 
although prejudicial to the animal economy. The sense of taste is 
intimately connected with that of touch and no less so with that of 
smell. Dr. Carpenter, writing of the sense of smell, observes, 
that — 
" A considerable part of the impression produced by many substances taken 
ii\to the mouth, is received through the sense of smell rather than through that 
of taste. Of this any one may easily satisfy himself, by closing the nostrils 
and breathing through the mouth only, whilst holding in his mouth, or even 
rubbing between his tongue and his ])alate, some aromatic substance ; its taste 
is then scarcely recognised, although it is immediately perceived when the 
nasal passages are re-opened, and its effluvia are drawn into them. There are 
many substances, however, which have no aromatic or volatile character, and 
whose taste, though not in the least dependent upon the action of the nose, is 
nevertheless of a powerful character. Some of these produce, by irritating 
the mucous membrane, a sense ])im(jcncy, allied to that which the same sub- 
stances (mustard, for instance) will produce when applied to the skin for a 
sufficient length of time, especially if the epidermis have been removed. Such 
sensations, therefore, are evidently of the same kind with those of touch, dif- 
fering from them only in the dc<ji ee of sensibility of the organ through which 
they are received. But there are others which produce sensations entirely dif- 
ferent from any that can be received through the skin, and which are properly 
distinguished, therefore, as yvstative ; such are common salt, which may be 
considered as a type of the saline taste ; sugar, the ty[)e of the saccharine ; 
quinine, of the bitter ; tannin, of the astringent; and citric acid, of the sour. 
AH such substances, therefore, are said to possess Hupkl properties, exciting 
distinctive tastes, quite irrespectively of any aromatic or odoriferous proper- 
ties which they may also possess, as well as of their stimulating action on the 
skill." * 
It is evident that while plants are being compressed between 
the teeth and the dental pad of a ruminant, their odoriferous as 
well as their other properties, affecting either touch or taste, 
* Carpenter's Manual of Physiology, second edition, p. 581. 
