NUTRITION. 397 



tions of one, who by his great discoveries in this department of 

 science, as well as by his extraordinary powers of combination, has 

 earned the right to be heard ; we need scarcely say that we refer to 

 Liebig. For even when facts were wanting, and when the em- 

 pirical data were unsettled and vacillating, the acuteness of his 

 intellect has frequently revealed secrets in nature which have 

 rarely failed, on subsequent investigation, to verify the correctness 

 of his views. 



NUTRITION. 



WE have already, in the beginning of this work, advanced the 

 proposition, that the study of the process of nutrition was the 

 crowning point or final aim of all our researches in physiological 

 chemistry ; but although all our previous considerations and all 

 our researches tended ultimately towards this point, we are still 

 far removed from it, nor shall we find that our exertions have been 

 rewarded with the success we might have hoped to achieve. Even 

 here we are compelled to rest satisfied with a mere sketch, which 

 notwithstanding a few sharply defined outlines, is still so imperfect 

 that it must be left very much to the imagination of individual 

 inquirers to fill up the deficiencies according to their own concep- 

 tion of what is needed for its completion, not forgetting that the 

 colours which are thus superadded must soon merge, according to 

 circumstances, into other tints, and can only be fully realised by 

 those who are familiar with the subject. 



In the course of our considerations we have acquainted our- 

 selves with all the substrata in which the animal processes are 

 effected ; we next endeavoured to ascertain the mutual relations of 

 the different substrata and processes in the accomplishment of the 

 most essential functions of animal life, both in their general and 

 special conditions, and we sought to study the parts assigned by 

 nature to each of the four great groups of substrata, or to their 

 individual members, within the animal organism. It would scarcely, 

 therefore, appear necessary to enter into any elaborate exposition 

 or investigation of those matters, which are necessary to the con- 

 tinuation or maintenance of vital motion when once induced, for 

 that which has once been exhausted can necessarily be replaced 



