142 THE POPULAR SCIENCE MONTHLY. 



the characters of the footprints belonging to each pace ; the transition 

 from one pace to another ; the modification of the movements incident 

 to pulling a load, etc., we are unable to notice here, and would therefore 

 refer the interested reader to M. Marey's work, where he will find the 

 subject fully elucidated. 



"- 



ODORS AND LIFE. 



BY FEENAND PAPILLON. 

 TRANSLATED FEOM THE MONITEUR SOIENTIFIQUE, BY A. E. MACDONOUGH. 



DESCARTES, Leibnitz, and all the great minds of the seventeenth 

 century, believed that phenomena are such interdependent parts 

 of one whole, that they require to be explained by each other, and 

 consequently, that a very close mutual connection should be main- 

 tained among the sciences. In their view, this was the condition of 

 rapid advance and intelligent development. The experimental method, 

 constant to systematic obstinacy in erecting so many barriers between 

 the different sections of natural philosophy, has greatly hindered the 

 completeness of whatever knowledge we possess as the result of mu- 

 tual interaction among all truths. At this day, such barriers are 

 tending to vanish of their own accord, and the science of man in his 

 relations with external media begins to show the outlines of its plan 

 and harmony. We have before this sketched several of its chapters, 

 and we will endeavor now to write another, on the subject of odors. 



The seat of smell, or the olfactory sense, is the pituitary membrane 

 lining the inner wall of the nostrils. It is a mucous surface, laid in 

 irregular wrinkles, and receiving the spreading, slender, terminal fila- 

 ments of a certain number of nerves. This membrane, like all other 

 mucous ones, constantly secretes a fluid designed to lubricate it. By 

 the aid of the muscles covering the lower part of the nostrils, the 

 apparatus of smelling can be dilated or contracted, precisely like that 

 of sight. This understood, the mechanism of olfaction is quite simple. 

 It consists in the contact of odorous particles with the olfactory nerve. 

 These particles are conveyed by the air to the inside of the nasal cav- 

 ities, and there strike upon the sensitive fibres. If the access of air 

 is prevented, or if the nerve is altered, no sensation is produced. Ex- 

 periments in physiology, in fact, have settled that the olfactory nerves 

 (or those of the first pair) are assigned exclusively to the perception 

 of odors. Loss of the sense of smell occurs whenever the nerves are 

 destroyed or injured by any process, or even whenever they are merely 

 compressed. On the other hand, it is a matter of common observation 



