ix THE DEBT OF SCIENCE TO DARWIN 471 



be due to a few simple instincts which necessarily lead to the 

 exact hexagonal cell with the base formed of three triangular 

 plates inclined at definite angles, on which so much mathema- 

 tical learning and misplaced admiration have been expended ; 

 and this explanation is no theory, but is the direct outcome 

 of experiments on the bees at work, as original as they were 

 ingenious and convincing. 



The Descent of Man and Later Works 



We must, however, pass on to the great and important work, 

 The Descent of Man and on Selection in Relation to Sex, which 

 abounds in strange facts and suggestive explanations; and 

 for the reader who wishes to understand the character and 

 bearing of Darwin's teachings, this book is the fitting supple- 

 ment to the Origin of Species and the Domesticated Animals and 

 Plants. To give any adequate account of this most remark- 

 able book and the controversies to which it has given rise, 

 would require an article to itself. We refer to it here in 

 order to point out what is not generally known, that its 

 publication was entirely out of its due course, and was not 

 anticipated by its author three years before. In the intro- 

 duction to Domesticated Animals (published in 1868), after 

 explaining the scope of that work, he tells us that in a 

 second work he shall treat of "Variation Under Nature," 

 giving copious facts on variation, local and general, on races, 

 sub-species and species, on geometrical increase, on the struggle 

 for existence, with the results of experiments showing that 

 diversity of forms enables more life to be supported on a 

 given area, while the extermination of less improved forms, 

 the formation of genera and families, and the process of 

 natural selection, will be fully discussed. This work would 

 have given all the facts on which chapters ii. to v. of the 

 Origin of Species were founded. In a third work he proposed 

 to show, in detail, how many classes of facts natural selection 

 explains, such as geological succession, geographical distribu- 

 tion, embryology, affinities, classification, rudimentary organs, 

 etc., etc., thus giving the facts and reasonings in full on 

 which the latter part of the Origin of Species was founded. 

 Unfortunately, neither of these works has appeared, and thus 

 the symmetry and completeness of the body of facts which 



