THE DOCTRINE OF VITAL UNITY. 151 



that they breathe, digest, have sensory reactions, 

 move essentially like animals, destroy and build up 

 in the same manner the immediate chemical prin- 

 ciples. For that purpose it was necessary to pass in 

 review, examining them from their foundation and 

 distinguishing the essential from the secondary, the 

 different vital manifestations digestion, respiration, 

 sensibility, motility, and nutrition. This is what 

 Claude Bernard did in his work Sur les Phenomenes 

 de la vie communs attx animaux et aux plantes. We 

 need only to sketch in broad outline the character- 

 istic features of his lengthy demonstration. 



Unity in tJte Formation of Immediate Chemical 

 Principles. The first and most important of the 

 differences pointed out between the life of animals 

 and that of plants was relative to the formation of 

 immediate principles. On this ground, indeed, vital 

 dualism raised its fortress. The animal kingdom 

 was considered in its totality as the parasite of the 

 vegetable kingdom. To J. B. Dumas, animals, 

 whatever they may be, make neither fat nor any 

 elementary organic matter ; they borrow all their 

 foods, whether they be sugars or starches, fats or 

 nitrogenous substances, from the vegetable kingdom. 

 About the year 1843 the researches of the chemists, 

 and of Payen in particular, succeeded in proving the 

 presence, almost constant, of fatty matters in vege- 

 tables ; and, further, these matters existed there in 

 proportions more than sufficient to explain how 

 the beast which fed upon them was fattened. The 

 chemists attributed to nature as much practical sense 

 as they themselves possessed ; and since the hay and 

 the grass of the ration brought fat ready made to the 

 horse, the cow, and the sheep, they declared that the 



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