ON THE GENETIC CYCLE. 



I. 



DERIVATION OF ORGANIC BEINGS. 



Although there is no distinction in Nature more clear or 

 more universally recognized than that between Organic and 

 Inorganic Bodies, yet, when we descend to the lowest forms 

 of the former, we find the marks which characterize them 

 as a class become at last so little appreciable, that there is 

 perhaps only one among those generally brought forward as 

 diagnostic, which may be looked for as universally present 

 — their derivation, by a process more or less direct, fi'om 

 previously existing individuals of a like kind. 



In a certain sense, indeed, derivation from like forms 

 may have place also in the origination of various substances 

 simply physical in their nature, but — to pass over other 

 difterences — there is this obvious distinction, that it is not 

 essential to their formation. When it has place, it may 

 facilitate their production more or less, as we find the 

 crystallization of a saline solution accelerated by the pre- 

 sence in it of crystals of the salt, already formed, which 

 serve as nuclei for additional deposits of the like kind ; but 

 such production will occur whenever the requisite chemical, 

 mechanical, and other physical agencies come to operate 

 upon matter in which the ultimate elements of the sub- 

 stances in question are present. 



B 



