396 RESPIRATION. 



in certain organisms nothing more than the inevitable conse- 

 quence of the chemical processes of the animal organism nothing 

 more than the final result of a movement regulated by definite 

 laws. 



We have purposely referred in brief terms to the different 

 theories of the respiration, as a fuller exposition of theoretical 

 questions and discussions would have been foreign to the plan of 

 this work (as we have already observed in our methodological intro- 

 duction) ; hence it has mainly been our object to limit ourselves to 

 the notice of facts which have become incorporated with science, 

 giving a critical opinion of their value wherever it was practicable 

 to do so. 



We have, therefore, endeavoured as far as possible, to consider 

 the scientific bases on which physiological chemistry has been 

 raised to the level which it now occupies. We purpose in the suc- 

 ceeding and closing section of this work, to notice the facts which 

 have led to the deductions of this or that theoretical conclusion, 

 without entering into a full exposition of the numerous theoretical 

 questions which are discussed at the present day. Nor do we 

 think that the time has yet arrived when a complete system of the 

 metamorphosis of animal matter can be given in a text-book of 

 physiological chemistry, and we should even be exceeding the 

 widest limits allowed to such a work, were we to take part 

 in the contest which is still waging concerning many of the 

 leading questions of the metamorphosis of animal matter, for as 

 we have already frequently remarked, the noblest labours of many 

 distinguished physicists show that we are still deficient in the first 

 exact physical and chemical bases of a theory of the metamorphosis 

 of animal matter. We abstain the more readily from a further 

 discussion of this subject, as we should otherwise be compelled to 

 add to the three volumes, of which our work already consists, still 

 another, which notwithstanding the exact bases laid down in the 

 three former volumes, must of necessity be a mere repetition of the 

 individual views of the author. All, therefore, who desire to ac- 

 quaint themselves with the discussions on the more general views 

 of vegetative life must familiarize themselves with the ground of 

 the contest, and learn for themselves, by carefully testing the evi- 

 dence on both sides, how to reach a higher and more comprehensive 

 point of view. But those who do not feel that they possess the 

 power of entering into such discussions, either as judges or com- 

 batants, will adopt the safest course if they accept the interpreta- 



