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.

The first part of the title of the first edition--“On the Origin of Species”--becomes “The Origin of Species” in the last edition, and is still further shortened to “Origin of Species” on the outside of the volume.

The form of the earlier editions was admirably suited for the purpose of attracting, and--so far as was possible with so difficult a subject--convincing, a large number of readers. When the subject was new and strange, the more numerous details of the last edition, and the smaller print which became necessary, would have acted as a hindrance to the complete success of the work. Authors and publishers are sometimes apt to forget that the form of a book has a great deal to do with the absorption of the ideas contained in it, especially when the argument is from the nature of the case difficult to follow, and the subject a new one. Francis Darwin in the “Life and Letters” justly condemns the unattractive form of the sixth edition of the work.