572. THE HISTORY OF BIOLOGY 



mentioned Ludwig Plate (born in i86i), Haeckel's disciple and successor 

 at Jena. After having applied his theoretical ideas to a number of special 

 investigations, both morphological and experimental, he summarized his 

 main arguments in an extensive work, Selektionsprinxif und Probleme der Art- 

 bildung, which may be said to contain all that can be adduced in modern 

 times in defence of the old Darwinism. And as its champion Plate has done 

 a great service, thanks to his wealth of knowledge, his strong convictions, 

 and his honesty. From the imperious disposition of his master, Haeckel, 

 he kept entirely free; he refused to employ the theory of selection to explain 

 the fundamental qualities of the living substance: assimilation, growth, res- 

 piration, etc., or indeed to explain variability or heredity; its sole function, 

 to his mind, is "to explain the origin of the teleological organizations, in 

 so far as they are not elementary qualities nor can be placed in the category 

 of Lamarckian factors." Darwin's greatest service, in his opinion, lies in 

 the fact that "he sought to explain organic finality out of natural forces, 

 to the exclusion of any metaphysical principle operating with conscious in- 

 telligence." Finality is thus the principal quality of organic life; adaptations 

 are expressly declared to represent a main difference between animate and 

 inanimate bodies. In his anxiety to defend the theory of selection, Plate 

 has, obviously without realizing it, hereby come perilously near Johannes 

 Miiller's old doctrine of finality and a far cry from Haeckel, who was at 

 one time prepared to characterize rudimentary organs as being the opposite 

 to profitable^ and the knowledge of them as "dysteleology." Plate, how- 

 ever, examines all the different kinds of finality — phenomena of correla- 

 tion, mechanical equiponderant apparatus, embryonic structures, instincts, 

 protective resemblance, and a good deal more — all this in order to find 

 proofs of the operation of natural selection. But if the theory of selection 

 is thus to stand or fall by the question of finality in nature, the result will, 

 of course, be that the function of selection automatically lapses if a different 

 view of natural phenomena is advanced. And, as has already been pointed 

 out, ever since the days of Democritus of old, research has constantly aimed 

 at seeking the existence of law-bound necessity in nature without any ex- 

 planations of purpose. But then, as Johannsen says, finality in an organism 

 becomes merely an expression for the fact that "organisms must be systems 

 in dynamic equipoise," that finality in general is self-evident in the very 

 fact of organization. From this standpoint one does not, of course, explain 

 by external causes the origin of functional adaptation in the organisms, 



^ Haeckel has made a special point of the human appendix as a proof of nature's lack of 

 finality; it serves no purpose, but produces only dangerous inflammations — an extremely in- 

 genuous argument. A healthy appendix, of course, plays its part in the renewal of substance, 

 and the danger of sometimes becoming inflamed is one to which any section of the intestine 

 whatever is exposed. 



