Darwin, too, wrote a very large number of memoirs for the scientific societies, as may be seen from the list in Appendix III. of the “Life and Letters,” but the volumes which he subsequently published included _all_ the previous details, with the addition of much new matter, and it is these volumes rather than the original communications which form the authoritative statement of his investigations. Such a method was possible and desirable with the subjects upon which he worked, all of which were of great interest to the thinking part of the general public, as well as to the experts; but in less attractive subjects it is not probable that the plan could be carried out in this country with any prospect of success. It has already been stated that Darwin looked on the “Origin of Species” as a short abstract of a greater work he intended to publish. It is likely that he at first contemplated a comprehensive work like the “Origin” itself, but soon found that his notes on domesticated animals and plants, the general results of which had been condensed into the first three chapters of the “Origin,” would form a work more than twice the size of the latter. He began arranging these notes on January 9th, 1860 (January 1st is the date given in the “Autobiography”), as soon as the second edition of the “Origin” was off his hands, but his “enormous correspondence,” as he calls it in the “Autobiography,” with friends about the “Origin,” and the reviews and discussions upon it, must have occupied a large part of his time; and then there was the third edition to bring out (published April, 1861). This edition must have cost much labour, as many parts were modified and enlarged to meet the objections or misunderstanding of reviewers. Francis Darwin tells us that the third chapter of “Animals and Plants, &c.,” was still on hand at the beginning of 1861. His work on this book was furthermore interrupted by illnesses and by other researches. Thus, during 1860 he worked at Drosera, and during the latter part of 1861 and beginning of 1862 at the fertilisation of orchids. In his diary for 1866 we meet with the entry, “_Nov. 21st_--Finished ‘Pangenesis,’” and later on, “_Dec. 22nd_--Began concluding chapter of book.” In this year, too, he brought out the fourth edition of the “Origin.” When the time for publication approached Darwin was much disappointed at the dimensions of the work. It was not published till January 30th, 1868, when it was proved that his fears were groundless, for a second edition of 1,250 copies were required in the following month, the 1,500 of the first edition having been all absorbed.