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.** Ina 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, 
