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another. And the vagueness, the inconstancy, the want of appre- 

 ciable structure, displayed by the simplest of living things as we 

 now see them, are characters (or absences of characters) which, on 

 the hypothesis of Evolution, must have been still more decided 

 when, asat first, no " forms," no " types," no " specific shapes," had 

 been moulded. That " absolute commencement of organic life on 

 the globe," which the reviewer says I " cannot evade the admission 

 of," I distinctly deny. The affirmation of universal evolution is in 

 itself the negation of an " absolute commencement " of anything. 

 Construed in terms of evolution, every kind of being is conceived as 

 a product of modifications wrought by insensible gradations on a 

 pre-existing kind of being ; and this holds as fully of the supposed 

 "commencement of organic life" as of all subsequent developments 

 of organic life. It is no more needful to suppose an " absolute 

 commencement of organic life" or a "first organism," than it is 

 needful to suppose an absolute commencement of social life and a 

 first social organism. The assumption of such a necessity in this 

 last case, made by early speculators with their theories of " social 

 contracts " and the like, is disproved by the facts ; and the facts, 

 so far as they are ascertained, disprove the assumption of such a 

 necessity in the first case. That organic matter was not produced 

 all at once, but was reached through steps, we are well warranted 

 in believing by the experiences of chemists. Organic matters are 

 produced iu the laboratory by what we may literally call artificial 

 evolution. Chemists find themselves unable to form these complex 

 combinations directly from their elements ; but they succeed in form- 

 ing them indirectly, by successive modifications of simpler combina- 

 tions. In some binary compound, one element of which is present 

 in several equivalents, a change is made by substituting for one of 

 these equivalents an equivalent of some other element ; so producing 

 a ternary compound. Then another of the equivalents is replaced, 

 and so on. For instance, beginning with ammonia, N H 3 , a higher 

 form is obtained by replacing one of the atoms of hydrogen 

 by an atom of methyl, so producing methyl-amine, N (C H 3 H 2 ) ; 

 and then, under the further action of methyl, ending in a 

 further substitution, there is reached the still more compound sub- 

 stance dimethyl-amine, N (C H,) (C H 3 ) Ii. And in this manner 

 highly complex substances are eventually built up. Another 

 characteristic of their method is no less significant. Two com- 

 plex compounds are employed to generate, by their action upon 

 one another, a compound of still greater complexity : different 

 heterogeneous molecules of one stage, become parents of a mole- 

 cule a stage higher in heterogeneity. Thus, having built up acetic 

 acid out of its elements, and having by the process of substitution de- 

 scribed above, changed the acetic acid into propionic acid, and propi- 

 onic into butyric, of which the formula is JqX m (n [ ; 



