514 THE HISTORY OF BIOLOGY 



enthusiasm for it knows absolutely no bounds; once he assures us outright 

 that, thanks to this theory, there is now not a single fact in organic life 

 that cannot be explained, although many are still unexplained. This en- 

 thusiasm, indeed, he shared with the whole of his generation; in a previous 

 chapter light has been thrown upon the hopes that the selection theory 

 aroused on its first appearance; the fact that in Haeckel they reached such 

 dizzy heights was due, of course, to his personal temperament, in which 

 enthusiasm, a naive self-satisfaction, and a blind confidence in the correct- 

 ness of his own ideas had been the predominant features since his youth. 

 Otherwise, he desired to a certain extent to modify the selection theory 

 itself, in so far as he would define more precisely the actual term "struggle 

 for existence." He urges the exclusion of all conditions belonging to sur- 

 rounding nature; the competition with other living creatures is all that 

 should be considered in this connexion. He further maintains the existence 

 of a competition ivithin the individual, between its various parts — that is, 

 an adaptation of the theory of correlation to Darwinism, which was later 

 developed in certain respects by others. And, finally, Haeckel insists, far 

 more emphatically than Darwin, upon the transformation of the individual 

 through the influence of environment and the inheritance of the modifica- 

 tions thus brought about; he defines evolution as a co-operation between an 

 " innerer Bildungstrieb" — heredity — and an " dusserer Bildungstrieb" — the 

 influence of environment. These expressions, which have a very natural- 

 philosophical and not a very mechanical sound, he borrowed, as he himself 

 admits, from Goethe's Pfianzenmefamorpbose, which he considers represents 

 Darwinism in mice, and which to his mind still forms the basis of plant 

 morphology — a view which at that time was shared by only a few sup- 

 porters of natural philosophy, but which has been repeated on Haeckel's 

 authority up to modern times by literary historians and other non-profes- 

 sionals. For the rest, he attributes to Darwinism an infinite mass of new 

 determinations, with their attendant terminology. Haeckel almost surpasses 

 Linnasus in his mania for classifying and naming, but he is entirely lack- 

 ing in the incomparable gift for form that the great systematist possessed; 

 most of his categories and nomenclature have not survived their originator, 

 although a number of them have been universally adopted, as for instance, 

 the terms "ontogeny" and "phylogeny," the former denoting the indi- 

 vidual's, the latter the race's development, and " cecology," as an expression 

 denoting the relation of living beings to their environment. Utterly absurd, 

 on the other hand is his " promorphological " classification of the life-forms 

 according to a symmetrical plan intended still further to confirm the alleged 

 similarity between the structure of crystals and organisms; the details of 

 this system, which, as a matter of fact, give evidence of a very superficial 

 knowledge of the foundations of crystallography, may be compared with 



