_The Saturday Review_ was much more moderate, by no means sharing the anxiety of those who regarded evolutionary theories as hostile to Christianity. The author is said 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 coexistence 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 independently 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 goes on to exemplify the survival of the fittest, though in other words. Mr. Patrick Matthew, in 1831, published a work on "Naval Timber and Arboriculture," in which he expressed, in scattered passages, a view nearly resembling Darwin's.