METAMORPHOSIS OF TISSUE. 201 



achieved in science during the last ten years, much yet remains to 

 be done beyond what qualitative chemical experiments or even 

 the most perfect theory of organic chemistry can supply ; for 

 notwithstanding the brilliant results attained in the science of 

 phytotomy and phyto-physiology, we are still entirely deficient in 

 exact experiments on the individual processes of vegetative life, 

 we require a more perfect method of quantitative chemical analysis 

 than we now possess, and we need scarcely make further allusion 

 to our ignorance of the conditions and circumstances under which 

 other molecular forces besides chemical affinity influence the 

 metamorphosis and formation of matter in the vegetable kingdom. 

 Yet notwithstanding the distance at which the aim of our inquiries 

 presents itself to our notice, we are convinced that the time will 

 soon arrive when that vital force, to which many have ascribed, 

 together with chemical phenomena, an active participation in 

 vegetable life, will be thoroughly eliminated, and when it will be 

 finally laid aside, never again to become the subject of scientific 

 consideration. 



GENERAL. REVIEW OF THE MOLECULAR MOTIONS IN THE 

 ANIMAL ORGANISM. 



WE have already (in the first volume) considered the material 

 substrata of animal life, in as far as they can be separated by 

 chemical means from the diversified group of substances wliich 

 combine to form animal bodies, and can be tested and accurately 

 determined by chemical reagents. We also endeavoured in the 

 same portion of our work to estimate the value of each separate 

 substance for animal life generally, us well as for the special pur- 

 poses of life, after having considered its origin and ultimate dis- 

 position in the living organism, and indicated the position which 

 it is entitled by its physiological importance to occupy amid this 

 great number of chemical agents. It therefore only remains for 

 us to notice in more general and more comprehensive terms the 

 reciprocal actions of these individual parts during the vital activity 

 of the organism, and their arrangement into a system of masses, 

 constantly acting upon one another and inducing definite results. 



In the second volume we turned our attention to the animal 

 juices, which from their mobile and fluid nature have been 



