ON THE GENKTIC VIEW OF NATURE. 303 



of his contemporaries which Darwin tlid, and for 

 which he indeed largely ])repared the way. Instead 

 of opposing the genetic change and development of 

 the forms of natural objects to their apparent fixity, 

 he rather reconciled botli views with each other by 

 maintaining^ "that in order to (jbtain a just insight 

 into the mutual affinities of animals it is Ijefore all 

 things necessary to distinguish the different tyijes of 

 organisation from the different grades of development." 

 He considered that "' " tlie idea of animal organisation 

 does not vary at equal intervals, but is realised in 

 certain principal forms which again break up into 

 variations of a lower u;rade " : and he ^ " arrived at the 

 four principal divisions of the animal kingdom estab- 

 lished by Cuvier." In 1828, in his work on the 'De- 

 velopment of Animals,' he discusses * " the prevalent 

 notion that the embryo of higher animals passes through 

 the permanent forms of the lower animals " — i.e., " the 

 doctrine of the agreement of individual metamorphosis 

 with the ideal metamorphosis of the whole animal 

 kingdom." Von Eaer had himself added greatly ^ to 



^ See Huxley's translation, loc. lesults : " It was von Baer who 



■c/t., p. 178. first clearly discriminated the great 



- Ibid., p. 182. events in a life-hi.^tory ; (a) the 



•' Ibid., p. 183. primary jjioeess of egg-cleavage, 



* See K. E. von Baer's ' Ueber and the establishment of the 



Entwickelungsgeschichte derThiere germinal layers; {b) the gradual 



BeobaclitungundReflexi<jn,'Konigs- differentiation of the tissues (hi.s- 



berg, 1828. The above extracts togenesis) ; and (c) the blocking 



are taken from the fifth scholion : out of the organs (organogenesis), 



" Ueber das Verluiltnissder Formen, , and the shape-taking of the entire 



die das Individuurii in den versdiie- 

 denen Stufen seiner Entwickelung 

 annimmt." See also Huxley's 

 Translation, loc. cit., pp. 186, 189. 

 ° Prof. J. A. Thomson sum- 

 marises as follows von Baers own 



organism (morphogenesis) (' Science 

 of Life,' p. 12'SJ. The classical 

 work of von Baer is dedicated to 

 his friend Pander, from whom and 

 DoUingcr he acknowledges iiaving 

 received the first impulses towards 



