Domain of Physiology. 243 



under the head of dynamics — a term which is thus employed 

 not only by the authors just cited, but by Clerk Maxwell, 

 Helmholtz, and Clifford*, and will be so used in the following 

 pages, while the term clynamicist will replace physicist. 



§ 18. Dynamics in the abstract regard matter in general, 

 without relation to species, the genesis of which is the office 

 of the chemical process or chemism. This gives rise to mine- 

 ralogical, or so-called chemical, species, which, theoretically, 

 may be supposed to be formed from a single element or 

 materia prima by the chemical process. 



" It is necessary to distinguish between the production of 

 new species differing in physical characters f and that repro- 

 duction 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 individuality, 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. Crys- 

 tallization is a commencement of individuation." 



"That mode of generation which produces individuals like 

 the parent can present no analogy to the phenomena under 

 consideration; metagenesis, or alternate generation, and meta- 

 morphosis are, 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 expansion and division, on the other. In the first case, 

 two or more bodies unite and merge their specific charac- 

 ters in those of a new species. In the second case, this pro- 

 cess is reversed, and a body breaks up into two or more new 

 species. Metamorphosis is, in like manner, of two kinds: in 

 metamorphosis by condensation only one species is concerned; 

 and in metamorphosis by expansion the result is homogeneous 

 and without specific difference. The chemical history of 

 bodies is a record of these changes ; it is, in fact, their 

 genealogy." 



" The processes of union and division embrace by far the 

 greater number of chemical changes, in which metamorphosis 

 sustains a less important part. By union, we rise to indefi- 

 nitely higher species ; but in division a limit is met with in 

 the production of species which seem incapable of further 



* W. K. Clifford, 'Essays/ ii. p. 17. This author, following the French 

 usage, employed the substantive Dynamic in a treatise on the subject thus 

 entitled ; but the plural form, Dynamics, is preferable, as serving to dis- 

 tinguish it from dynamic used adjectively. 



t That is to say, differing in dynamic relations. 



