Thoughts on Species. 379 



■established are truths — we should conceive of a species from the 

 potential point of view, and regard it as — 



a. A concentered unit of force, an ineffaceable component of 

 the system of nature ; but 



5. Subject to greater or less librations according to the uni- 

 versal law of mutual reaction or sj^mpathy among forces. 



And, in addition, in the organic kingdom, 



c. Exhibiting its potentiality not simply or wholly in any exist- 

 ing condition or action, but through a cycle of growth from the 

 primal germ to maturity, when the new germ comes forth as a 

 repetition of the first to go another round in the cycle and per- 

 petuate the original unit ; and, therefore, as follows from a ne- 

 cessary perpetuity of the cycle — 



d. Exhibiting identity of species among individuals by per- 

 petuated fertile intermixture in all normal conditions, and non- 

 identity by the impossibility of such intermixture, the rare cases 

 of continuation from one or two generations, attesting to the sta- 

 bility of the law, by proving the effort of nature to rid herself 

 of the abnormity, and her success in the effort. 



e. The many hke individuals that are conspecific do not pro- 

 perly constitute the species, but each is an expression of the spe- 

 cies in its potentiality under some one phase of its variables ; and 

 to understand a species, we must know its law through all its cy- 

 cle of growth, and its complete series of librations. 



We should therfore conceive of the system of nature as in- 

 Tolving, in its idea, a system of units, finite constituents at the 

 basis of all things, each fixed in law; these units in organic 

 nature as adding to their kinds by combinations in definite pro- 

 positions ; and those in organic nature adding to their "numbers of 

 representative individuals, but not kinds, by self-reproduction ; 

 and all adding to their varieties by mutual reaction or sympathy. 

 Thus from the law within and the law without, under the Being 

 above as the Author and sustainer of all law,,the world has its 

 diversity, the cosmos its fullness of beauty. 



I would remark again that we must consider this mode of 

 reaching truth, by reasoning from the general to the special, a s 

 requiring also its complement, direct observation, to give un- 

 wavering confidence to the miiid ; and we should therefore en- 

 courage research with a wiUingness to receive whatever results 

 come from nature. We should give a high place in our estimate 

 to all investigation tending to'elucidate the variation or perma- 



