282 THE SENSORIAL FUNCTIONS. 



the nicest balance will not show the smallest increase of its 

 weight from this impregnation. No facts in natural philo- 

 sophy afford more striking illustrations of the astonishing, 

 and indeed inconceivable divisibility of matter, than those 

 relating to odorous effluvia. 



It would appear that most animal and vegetable bodies are 

 continually emitting these subtle effluvia, of which our own 

 organs are not sufficiently delicate to apprize us, unless 

 when they are much concentrated, but which are readily 

 perceived and distinguished by the lower animals; as may 

 be inferred from their actions. A dog is known to follow 

 its master by the scent alone, through the avenues and turn- 

 ings of a crowded city, accurately distinguishing his track 

 amidst thousands of others. 



The utility of the sense of smell is not confined to that of 

 being a check upon the respiration of noxious gases; for it 

 is also a powerful auxiliary to the sense of taste, which, of 

 itself, and without the aid of smell, would be very vague in 

 its indications and limited in its range. What may have 

 been its extent and delicacy in man, while he existed in a 

 savage state, we have scarcely any means of determining; 

 but in the present artificial condition of the race, resulting 

 from civilization and the habitual cultivation of other sources 

 of knowledge, there is less necessity for attending to its per- 

 ceptions, and our sensibility to odours may perhaps have di- 

 minished in the same proportion. It is asserted both by 

 Soemmerring and Blumenbach that the organ of smell is 

 smaller in Europeans, and other civilized races of mankind, 

 than in those nations of Africa or America, which are but 

 little removed from a savage state: it is certainly much less 

 developed in man than in most quadrupeds. To the carni- 

 vorous tribes, especially, it is highly useful in enabling them 

 to discover their natural food at great distances. 



The cavity of the nostrils, in all terrestrial vertebrated 

 animals is divided into two by a vertical partition; and the 

 whole of its internal surface is lined by a soft membrane, 



