Of the three remaining chapters before the XIVth, and last, which contains the Recapitulation and Conclusion, two--XI. and XII.--are concerned with Geographical distribution, while the XIIIth deals with Classification, Morphology, Embryology and Rudimentary Organs. These three chapters are almost entirely devoted to the proof that the facts of Nature with which they deal are not inconsistent with, but rather support, and often strongly support, a belief in Organic Evolution. Hence we see that this, incomparably the greatest work which the biological sciences have seen, begins with an explanation and defence and definition of the sphere of natural selection--then passes to consider difficulties which are partly those of natural selection, and partly of organic evolution--while it finally treats of the evidences of the latter process and the difficulties which a belief in it encounters. This arrangement was a very wise one for a book which was intended to convince a large circle of readers; for the human mind so craves after an explanation, that it was of more importance for the success of the work to show first that an intelligible cause of evolution had been proposed, than to follow the more logical order of first setting forth the evidences of evolution. The second edition (fifth thousand) was issued in January, 1860, the third (seventh thousand) in 1861, the fourth (eighth thousand) in 1866, the fifth (tenth thousand) in 1869, the sixth in 1872: in 1887 the twenty-fourth thousand was reached. A note to the last edition states that the second “was little more than a reprint of the first. The third edition was largely corrected and added to, and the fourth and fifth still more largely.” The sixth edition also contains “numerous small corrections,” and is about one-fourth larger than the first edition, although this material is, owing to the smaller print and more crowded lines, compressed into a smaller number of pages. The sixth edition also differs from the first in containing a glossary, an historical sketch, and a note and list of the chief corrections. The titles of Chapters I., II., and III. remain the same in the first and last editions. Herbert Spencer’s phrase is added to Darwin’s term, as the heading of Chapter IV., which accordingly becomes in the last edition “Natural Selection; or the Survival of the Fittest.” This change was certainly introduced in order to help readers to grasp the meaning of Darwin’s title, which had been very generally misunderstood. The heading of Chapter V. remains the same, while in Chapter VI.--“Difficulties on Theory”--“on” is replaced by “of the.” This chapter is, in the last edition, succeeded by a new one dealing with many of the difficulties which had been raised or had occurred to Darwin in the interval between the two editions; it is headed “Miscellaneous Objections to the Theory of Natural Selection.” The titles of the remaining eight chapters are unchanged.