OPERATION OF CHEMICAL FORCES IN THE LIVING BODY. 117 



cesses of nutrition, is likely to have an important influence in determining 

 further chemical changes, in virtue of the galvanic action which may thus be 

 set up; it having been shown by Becquerel that, if the bend of a siphon be 

 filled with fine sand, and an acid be poured into one leg and an alkaline solution 

 into the other, the chemical action which ensues at their point of meeting will 

 give rise to a galvanic current between the contents of the two legs, when these 

 are connected by a wire passing from one to the other through the open ends of 

 the siphon. As the blood and the tissues are continually acting chemically on 

 one another through the permeable walls of the vessels, it is scarcely possible 

 but that electric currents should be thus generated; and it seems very probable 

 that these may perform an important part in the metamorphoses in question. 



93. On the whole it may be confidently affirmed, that of the changes which 

 have been described in the present chapter, there are none save the production 

 of Fibrin, whose peculiarly vital properties have been already dwelt on ( 29) 

 which there is any adequate reason to attribute to other than Chemical agencies ; 

 for if all cannot yet be precisely imitated by laboratory processes, this imitation 

 has been successfully practised in the case of a large number of them ; and the 

 nature of the remainder is such as leaves it by no means improbable that they 

 too will be reduced to the same category. In treating of this subject, it would 

 be very easy to obtain a temporary solution of all difficulties of this kind, by 

 regarding every case not otherwise explicable as a manifestation of " vital force ;" 

 but such a method is altogether inconsistent with sound philosophy ; and we 

 have no right to call in the assistance of vital force on any other occasion than 

 when we witness phenomena which are not only inexplicable by, but altogether 

 inconsistent with, the known operations of Physical and Chemical forces. 

 Phenomena of this kind will hereafter come under our consideration ; but none 

 such (with the single exception just referred to) have yet fallen under our notice; 

 the metamorphoses we have been considering being mere changes in composition, 

 analogous to those which have been effected in the laboratory; and the elements 

 alike of the original substances, and of the products of their changes, being 

 held together by affinities in which Life has obviously no concern. It is not 

 here denied, however, that Vital Force has an influence upon the Chemical phe- 

 nomena of the body; on the contrary, much evidence will be hereafter given, 

 that such an influence is exerted, especially through the nervous system. But 

 this agency may be considered to operate, after the manner of Electricity or 

 Heat, in modifying the play of ordinary Chemical attractions, rather than in 

 substituting for them a new set of "vital affinities." 



94. The highest estimate, however, that we seem justified in making, of the 

 play of Chemical Affinities in the living body, is applicable only to those trans- 

 formations, which, on the one hand, prepare the pabulum for that Organizing 

 process, whereon is dependent the development of vital properties in substances 

 that were previously inert; and which, on the other, minister to the application 

 of the effete matters, resulting from the disintegration of tissues whose term of 

 life is over, to purposes that are advantageous to the system in general, or are 

 subservient to their removal in the most effective manner from the economy, to 

 whose operations their continued presence would be prejudicial. Thus the re- 

 duction of all the protein compounds to the condition of Albumen, in the diges- 

 tive process, and the introduction of this substance into the blood in its soluble 

 form, can be accounted nothing else than a purely chemical operation. The 

 same may be said of the conversion of starch into sugar, and of sugar into 

 fatty matter. It may be surmised, moreover, that the production of globulin 

 and of haematin from albuminous material, may be due to chemical actions de- 

 termined by the vital agency of the floating cells of the blood, in the manner 

 indicated in the preceding paragraph. And the same may be true of the change 

 of composition (if any difference really exists), which is a part of the metamor- 



