VITAL PHENOMENA. IQ5 



influence of the intrinsic conditions appears quite 

 as clearly. As we have seen, this is so that the 

 requisite fundamental materials may be spent by 

 each element in suitable proportions, water, chemical 

 compounds, air, and heat, that organs may be added 

 to organs, and that apparatus may be set to work in 

 complex structures. Why a digestive apparatus? 

 To prepare and introduce into the internal medium 

 liquid materials which are necessary to life. Why a 

 respiratory apparatus? To impart the vital gas 

 necessary to the cells, and to expel the gaseous 

 excrement, the carbonic acid which they reject. 

 Why a circulatory apparatus? To transport and 

 renew this medium throughout. The apparatus, the 

 functional wheels, the vessels, the digestive and 

 respiratory mechanisms do not exist for themselves, 

 like the random sketches of an artistic nature. They 

 exist for the innumerable anatomical elements which 

 people the economy. They are arranged to assist 

 and more rigorously to regulate cellular life with 

 respect to the extrinsic conditions which it demands. 

 They are, in the living body, as in civilized society, 

 the manufactories and the workshops which provide 

 for the different members of society dress, warmth, 

 and food. In a word, the law of tJie construction of 

 organisms or of the bringing to perfection of an 

 organism is the same as the law of cellular life. It 

 is otherwise suggestive as the law of division of 

 physiological labour formerly enunciated by Henry 

 Milne-Edwards; and in every case it has a more 

 concrete significance. Finally, it brings the organic 

 functional activity into relation with the conditions of 

 the ambient medium. 



How Experiment acts on the Phenomena of Life. 



