308 SCIENTIFIC THOUGHT. 



upon this order as systematic only, and ideal ; l he thinks 

 merely of arrangement or " taxonomy." We may say 

 that he deals with phylotaxy (called at that time tax- 

 onomy), not with phylogenesis. He conceives that onto- 

 genesis, the historical development of the individual 

 thing, throws light on the " mutual relations of organ- 

 ised bodies"; 2 he wishes to make ontogenesis helpful 

 in taxonomy or in phylotaxy. This term did not then 

 exist, but it is useful in order to enable us to under- 

 stand the change which came over natural science when 

 is. the attempts at phylotaxy were succeeded by the schemes 



Phylotaxy 



and phyio- of phylogenesis, when reasons were established for taking 



gene-sis. 



in real earnest the idea then fancifully 3 put forward that 

 the natural order of living beings represented the order 

 in which they had developed out of each other in time. 

 These reasons did not at that time exist. 



A suggestion in this direction had indeed been thrown 

 out, and an elaborate theory had been published about 



1 In his later writings von Baer that of the ' ' fieri " (processes of 



notes especially the difference be- ! change and development). See the 



tween a purely ideal and a genetic J expositions in the introduction to 



or genealogical relationship. See | the article on Darwin. He there 



' Reden, &c.,' vol. ii. p. 386 (2nd ed. ) I also mentions Meckel and Oken as 



2 'Entwickeluugsgeschichte' j the two principal exponents of the 



(1828), p. 231; transl., p. 221. | extreme view then put forward and 



3 In a later publication of von i opposed by himself, that the human 



Baer's (see ' Reden, &c.,' 2 Theil, ! being in its development passes 



No. V., "Ueber Darwin's Lehre") through the different higher forms 



the aged author tries to define more of the animal creation, and he 



exactly the part which his early | maintains that Johannes Miiller, 



writings played in the gradual | who had in the first edition of his 



establishment of a genetic concep- i ' Physiology ' accepted this view, 



tion of nature. If Haller arrived ' struck it out in the second. He 



ultimately at the dictum " es gibt ' also refers to a passage in a Memoir 



kein Werden," we may say that von ' of 1859, published just before the 



Baer as emphatically asserted the ! appearance of the ' Origin of 



opposite, that "es gibt kein Sein. " Species,' in which he maintains his 



In Baer we have progressed from the belief " that formerly organic forms 



study of the " esse " (fixed forms) to i were less rigid." 



