700 APPENDIX D. 



this complex componnd, by operating on another complex 

 compound, such as the dimethyl- amine named above, gene- 

 rates one of still greater complexity, butyrate of dimethyl-amine 



] C O (hM)' ^3) H j. n (c H3) {C H3) H. See, then, the re- 



markable parallelism. The progress towards higher types of or- 

 ganic molecules is effected by modifications upon modifications ; 

 as throughout Evolution in general. Each of these modifications is 

 a change of the molecule into equilibrium with its environment — an 

 adaptation, as it were, to new surrounding conditions to which it is 

 subjected ; as throughout Evolution in general. Larger, or more 

 integrated, aggregates (for compound molecules are such) are suc- 

 cessively generated ; as throughout Evolution in general. More 

 complex or heterogeneous aggregates are so made to arise, one out 

 of another ; as throughout Evolution in general. A geometrically- 

 increasing multitude of these larger and more complex aggregates 

 so produced, at the same time results ; as throughout Evolution in 

 general. And it is by the action of the successively higher forms 

 on one another, joined with the action of environing conditions, that 

 the highest forms are reached ; as throughout Evolution in general. 

 When we thus see the identity of method at the two extremes 

 — when wc see that the general laws of evolution, as they are exem- 

 plified in known organisms, have been unconsciously conformed to 

 by chemists in the artificial evolution of organic matter ; we can 

 scarcely doubt that these laws were conformed to in the natural 

 evolution of organic matter, and afterwards in the evolution of the 

 simplest organic forms. In the early world, as in the modern 

 laboratory, inferior types of organic substances, by their mutual 

 actions under fit conditions, evolved the superior types of organic 

 substances, ending in organizable protoplasm. And it can hardly 

 be doubted that the shaping of organizable protoplasm, which is a 

 substance modifiable in multitudinous ways with extreme facility, 

 went on after the same manner. As I learn from one of our 

 first chemists, Prof. Frankland, protein is capable of existing 

 under probably at least a thousand isomeric forms; and, as 

 we shall presently see, it is capable of forming, with itself 

 and other elements, substances yet more intricate in composi- 

 tion, that are practically infinite in their varieties of kind. 

 Exposed to those innumerable modifications of conditions which 

 the Earth's surface afforded, here in amount of light, there in 

 amount of heat, and elsewhere in the mineral quality of its aqueous 

 medium, this extremely changeable substance must have undergone 

 now one, now another, of its countless metamorphoses. And to the 

 mutual influences of its metamorphic forms under favouring con- 

 ditions, we may ascribe the production of the still more composite, 

 still more sensitive, still more variously- changeable portions of 

 organic matter, which, in masses more minute and simpler than 



