392 POISONS, CONTAGIONS, MIASMS. 



araorphosis. We have just seen that the contact of 

 oxalic acid with oxamide caused the production of 

 fresh oxalic acid, which in its turn exercised the 

 same action on a new portion of oxamide. The 

 transformation was only arrested in consequence of 

 the quantity of oxamide present being limited. In 

 their form both these transformations belong to the 

 same class. But no one except a person quite unac- 

 customed to view such changes will ascribe them to 

 a vital power, although we admit they correspond 

 remarkably to our common conceptions of life ; they 

 are really chemical processes dependent upon the 

 common chemical forces. 



Our notion of life involves something more than 

 mere reproduction, namely, the idea of an active 

 power exercised hy virtue of a definite fornix and 

 production and generation in a definite form. By 

 chemical agency we can produce the constituents of 

 muscular fibre, skin, and hair ; but we can form by 

 their means no organized tissue, no organic cell. 



The production of organs, the cooperation of a 

 system of organs, and their power not only to pro- 

 duce their component parts from the food presented 

 to them, but to generate themselves in their original 

 form and with all their properties, are characters 

 belonging exclusively to organic life, and constitute 

 a form of reproduction independent of chemical 

 powers. 



The chemical forces are subject to the invisible 

 cause by which this form is produced. Of the exist- 

 ence of this cause itself we are made aware only by 

 the phenomena which it produces. Its laws must be 

 investigated just as we investigate those of the other 

 powers which effect motion and changes in matter. 



The chemical forces are subordinate to this cause 

 of life, just as they are to electricity, heat, mechan- 

 ical motion, and friction. By the influence of the 

 latter forces, they suffer changes in their direction, 

 an increase or diminution of their intensity, or a 

 complete cessation or reversal of their action. 



