The Wallace-Darwin Correspondence 



cast of much of his reasoning; and I know not why, but 

 I never feel convinced by deduction, even in the case of 

 H. Spencer ^s writings. If Dr. B.'s book had been turned 

 upside down, and he had begun with the various cases of 

 heterogenesis, and then gone on to organic and afterwards 

 to saline solutions, and had then given his general argu- 

 ments, I should have been, I believe, much more influenced. 

 I suspect, however, that my chief difficulty is the effect of 

 old convictions being stereotyped on my brain. I must 

 have more evidence that germs or the minutest fragments 

 of the lowest forms are always killed by 212° of Fahr. 

 Perhaps the mere reiteration of the statements given by 

 Dr. B. by other men whose judgment I respect and who have 

 worked long on the lower organisms would suffice to convince 

 me. Here is a fine confession of intellectual weakness ; but 

 what an inexplicable frame of mind is that of belief. 



As for Rotifers and Tardigrades being spontaneously 

 generated, my mind can no more digest such statements, 

 whether true or false, than my stomach can digest a lump 

 of lead. 



Dr. B. is always comparing archebiosis as well as 

 growth to crystallisation; but on this view a Rotifer or 

 Tardigrade is adapted to its humble conditions of life by 

 a happy accident; and this I cannot believe. That ob- 

 servations of the above nature may easily be altogether 

 wrong is well shown by Dr. B. having declared to Hux- 

 ley that he had watched the entire development of a leaf 

 of Sphagnum. He must have worked with very impure 

 materials in some cases, as plenty of organisms appeared 

 in a saline solution not containing an atom of nitrogen. 



I wholly disagree with Dr. B. about many points in his 

 latter chapters. Thus the frequency of generalised forms 

 in the older strata seems to me clearly to indicate the com- 

 mon descent with divergence of more recent forms. 



275 



