71 o THE POPULAR SCIENCE MONTHLY. 



MODEEN PHILOSOPHICAL BIOLOGY. 



By Db. E. gazelles, 

 translated from the french bt j. fitzgerald, a. m. 



n. 



"VTOT all matter is capable of performing vital acts. Those sub- 

 -LM stances alone possess this property which, owing to their pecul- 

 iar composition, readily undergo molecular changes; that is to say, 

 whose parts are grouped in very unstable equilibrium, and which 

 are always ready to form other combinations. This state of insta- 

 bility is the result of complex combinations of six simple bodies, 

 which at common temperatixres have a very weak affinity for one 

 another, but a strong affinity for elements outside of these combi- 

 nations. Of the six, four, namely oxygen, hydrogen, carbon, and 

 nitrogen, enter into these combinations in large proportions, while of 

 the other two, namely sulphur and phosphorus, only a few atoms enter; 

 and these latter elements are so readily oxidized that their presence 

 increases the instability of the compound. Besides, the atoms of 

 these simple bodies, though occurring in identical proportions, may be 

 grouped according to different modes of aggregation (isomerism and 

 polymerism), and the organic compounds which they make up stand 

 midway between liquids and solids ; their molecules are highly incon- 

 stant, whence result two well-known properties : the plasticity of 

 organic matter, and its permeability to other substances. These 

 properties are further causes of instability, inasmuch as they expose 

 the organic substances to a number of disturbing influences. Thus, 

 organic matter is not only subject to decomposition by light and heat, 

 but also by the direct or indirect chemical action of bodies entering 

 it, or acting on it from without. In such cases the effect of the dis- 

 turbance is to cause the organic substance to pass from a state of rela- 

 tive instability to one of relative stability, or even to the state of com- 

 pounds the most stable in the organic world. 



At the same time that it undergoes the action of these external 

 forces and among external forces we include those developed in 

 organized beings, but applied to other tissues than those producing 

 them at the same time that under the action of these external forces 

 organic matter suffers decomposition, it becomes the scene of no- 

 table reactions. Even very inconsiderable changes in the external 

 forces, which serve as its conditions, produce in it new molecular 

 arrangements which offer a contrast, in their extent and importance, 

 to the comparative insignificance of their cause. These new arrange- 

 ments, being succeeded by more stable combinations, in turn bring 

 about a disengagement of a great amount of force, in passing from 



