96 LIFE OF 



to have encountered the difficulties of his theory " with 

 admirable skill and ability," and though The Saturday 

 remained unconvinced of his general argument, yet it 

 acknowledged itself "persuaded that natural selection 

 must henceforward be admitted as the chief mode by 

 which the structure of organised beings is modified in a 

 state of nature ; " and thought it very possible that, 

 through its agency, considerable groups of nearly 

 allied species might have been derived from a single 

 progenitor : but there The Saturday stopped, believing 

 in limits to this power. 



The second edition of " The Origin of Species," which 

 appeared in January, 1860, only six weeks after the first, 

 contained but few alterations ; the third, in March, 1861, 

 had received extensive additions and corrections. The 

 most important of these discussed the so-called tendency 

 of organisation to advance, and explained the present co- 

 existence of high and lowly organised forms. A valuable 

 historical sketch of the modern progress of opinion on 

 the subject, from Lamarck's time, was prefixed to the 

 book. It was further enlarged in subsequent editions, as 

 evidences accumulated that various thinkers had inde- 

 pendently adopted the evolution theory, or the more 

 special one of natural selection. Notable instances 

 of anticipation were those of Dr. Wells, who, in a 

 paper read before the Royal Society in 1813, but not 

 published till 1818, had expressed the opinion that all 

 animals tend to vary ; that agriculturists improve breeds 

 by selection ; and that what they do by art " seems to be 

 done with equal efficacy, though more slowly, by nature, 

 in the formation of varieties of mankind." He then 



