a,'^*^*^^''^ V and on Equivalent Volumes. > ^ ,|/ 527 



gravity, and the relations of heat, light, electricity and magnetism. 

 A description of these qualities and relations constitutes the 

 physical history of matter, and the group of characters which 

 serve to distinguish one species from another, may be designated 

 the apparent form of a species, as distinguished from its essential 

 form. 



The forces above mentioned modify physically the specific 

 characters of matter, but they have besides important relations 

 to those higher processes, which give rise to new species by a 

 complete change in the specific phsenomena of bodies. In the 

 capacity of this complete change, consists the chemical activity 

 of matter. 



It is necessary to distinguish between the production of new 

 species differing in physical characters, and that- reproduction 

 which belongs to organic existences. The distinction arises from 

 that individuation which marks the results of organic life, and 

 is eminently characteristic of its higher forms. The indivi- 

 duality not only of the organism, but of its several parts, is more 

 evident as we ascend the scale of organic life, while inorganic 

 bodies have a specific existence, but no individuality ; division 

 does not destroy them. Solidity or crystallization is a com- 

 mencement of individuation, and crystals like the tissues of 

 plants and animals, must be destroyed before they can become 

 the subjects of chemical change ; " corpora non agunt nisi sint 

 soluta" 



That mode of generation which produces individuals like the 

 parent, can present no analogy to the phsenomena under con- 

 sideration; metagenesis or alternate generation*, and metamor- 

 phosis, are perhaps, however, to a certain extent prefigured in the 

 chemical changes of bodies. Their metagenesis is effected in two 

 ways, by condensation and union on the one hand, and by expan- 

 sion and division on the other. In the first case, two or more bodies 

 unite, and merge their specific characters in those of a new 

 species. In the second case, this process is reversed, and a 

 body breaks up into two or more new species. Metamorphosis 

 is in the same manner of two kinds ; in metamorphosis by con- 

 densation, only one species is concerned ; and in that by expan- 

 sion the result is homogeneous, and without specific difi'erence. 

 ^^j.The chemical history of bodies is a record of these changes; 

 n^t is in fact their genealogy. The processes of union and divi- 

 sion embrace by far the greater number of chemical changes, in 



* The term metagenesis I find used by Prof. Owen to designate that 

 tbultiform or serial generation observed in many of the lower orders of 

 animal life. This, however, is not strictly a metagenesis, and the term, if 

 not rightly understood, may lead to dangerous errors ; as appUed to chemical 

 transformations, however, it appears unohjectionable. 



