164 THE DOCTRINE OF DESCENT. 



duction of protoplasm, that primordial organism, from 

 the atoms of its constituents. 



Hence the beginning of life at some bygone period 

 is likewise not susceptible of demonstration ; but the 

 commencement of animate being at some definite era 

 of development is a logical necessity, and by no means 

 a vulnerable point in the doctrine of Descent.^'' 



We have already incidentally mentioned a man who, 

 although not so eminent as Darwin, has the glory of 

 having independently discovered the law of natural 

 selection, and of having, after Darwin had come forward 

 with his fundamental work, supported the theory of 

 selection by a profusion of original observations. This is 

 Alfred Russell Wallace.^^ In a paper, published in 1855, 

 he demonstrated the dependence of the flora and fauna 

 on the geographical position and geological nature of 

 the district of propagation, and the close connection of 

 the species, according to time and habitat, with kindred 

 species previously existing ; and in a second work, in 

 the year 1858, on the inclination of varieties to deviate 

 without limit from the original type, we find a dis- 

 quisition on the importance of the struggle for exist- 

 ence, the consequences of adaptation, the selection of 

 the most useful, and the replacement of the earlier 

 species by the establishment of the more valuable 

 varieties. We shall repeatedly have occasion to draw 

 upon the rich supplies of his researches. 



