NUTRITION. 12T 



that change which fits it -for the purpose of nutrition r 

 converts if from dead matter into organized living parti- 

 cles ? Or is this change wrought gradually ? 



Dr. B. In all probability, this change is not effected 

 at any particular stage in the route which the aliment 

 pursues, but is accomplished gradually by the various 

 processes to which it is subjected before it reaches its 

 ultimate destiny. When fully and perfectly animalized, 

 it furnishes the materials whence all the parts of the body 

 whatever may be their nature or situation, are to receive 

 their supplies. From the vessels which circulate in the 

 bones, bony matter is deposited ; in the liver, it is bile ; 

 in the salivary glands, it is saliva, &c. 



Emily. Again I must express my surprise, that amidst 

 this great variety of chemical changes, this play of innu- 

 merable affinities, there is nothing of interference or con- 

 fusion. How wonderful ! how mysterious ! 



Dr. B. To heighten the mystery still more, we find 

 substances not contained in the blood, and which, chem- 

 istry, having gone to the utmost limits of analysis, has 

 been contented to call simple bodies. The uniform 

 composition of animals is also an exceedingly strange 

 fact. The flesh and bones of a sheep, as we have be- 

 fore observed, whose diet is exclusively vegetable ; of a 

 lion, which subsists on the flesh of animals ; and of a 

 hog, which lives upon a mixed diet, exhibit the same 

 chemical composition, and are formed by processes 

 which chemistry has never been able to imitate. As but 

 little or no nitrogen is taken into the system in respira- 

 tion, it is inexplicable how this substance should enter as 

 much into the composition of herbivorous, animals in 

 whose food only a small quantity of nitrogen exists, as 

 in that of carnivorous animals in whose food this princi- 

 ple greatly abounds. Lime likewise, is found in the 

 body in sometimes double the quantity of what is con- 

 tained in the food. 



Emily. The living system may be considered I think, 

 a, real laboratory which enchains our admiration at the. 



