ON THE GENETIC VIEW OF NATURE. 



349 



sense by Meckel, von Baer, and Series. It has some- 

 times been termed von Baer's law, though von Baer 

 very carefully guarded himself against many popular 

 versions of the analogy, applying it only within the 

 limits of the four great groups or plans of organisation 

 into which he divided the animal kingdom. 1 In hi& 



zustande der hiJheren Thiere und 

 dem permanenten der niederen 

 stattfindenden Parallels' (1811): 

 " There is no good physiologist who 

 has not been struck by the observa- 

 tion that the original form of all 

 organisms is one and the same, and 

 that out of this one form all, the 

 lowest as well as the highest, are 

 developed in such a manner that 

 the latter pass through the per- 

 manent forms of the former as 

 transitory stages. Aristotle, Hal- 

 ler, Harvey, Kielmeyer, Autenrieth, 

 and many others, have either made 

 this observation incidentally, or, 

 especially the latter, have drawn 

 particular attention to it, and 

 drawn therefrom results of per- 

 manent importance for physiology." 

 Louis Agassiz, in his celebrated 

 "Essay on Classification" (1859), 

 though rejecting the doctrine of 

 descent, "insisted, nevertheless, on 

 the correspondence between stages 

 in embryonic development and the 

 grades of differentiation expressed 

 in the classification of living and 

 extinct animals " (Thomson, ' The 

 Science of Life,' p. 134). 



1 " A careful examination of von 

 Baer's ' laws ' shows that he did 

 not accept the recapitulation with- 

 out many saving clauses. He be- 

 lieved in it much less than many 

 a modern embryologist, such as F. 

 M. Balfour or A. Milnes Marshall " 

 (Thomson, p. 133). Before the 

 publication of Haeckel's ' Generelle 

 Morphologic ' the naturalist who 

 seems to have most clearly ex- 

 pressed the recapitulation theory 



was Fritz Miiller, who in 1864 

 published his famous tract ' Fur 

 Darwin,' which appeared in 1868 

 in an English translation by Dallas, 

 with the title ' Facts and Argu- 

 ments for Darwin.' The work of 

 Fritz Miiller, who for many years 

 lived in the Brazils, isolated and 

 secluded, and devoted to scientific- 

 observation, was welcomed by Dar- 

 win as one of the first and greatest 

 supports to his doctrine : the 

 author was singled out by him as 

 the " prince of observers," and 

 frequently referred to in the later 

 editions of the 'Origin of Species.' 

 Delage considers him to have first 

 expressed the fundamental bio- 

 genetic law (' L'HerediteY pp. 159, 

 469), and this is in agreement with 

 Haeckel's own declaration in the 

 13th chapter of the 'History of 

 Creation.' It is, however, well to 

 mention that the recapitulation 

 theory has found little favour with 

 botanists ; that Haeckel himself 

 admits that the parallelism be- 

 tween ontogenesis and phylogenesis 

 is general and not exact ; that there 

 is a tendency to abbreviation ; that 

 recent adaptations (called by him 

 " kainogenetic ") may mask more 

 ancient (" palingenetic ") features, 

 &c. See J. A. Thomson, 'The 

 Science of Life,' p. 135. Ziegler, 

 in his recent excellent review of 

 the ' Present Position of the Doc- 

 trine of Descent ' (Jena, 1902, p. 12), 

 admits that the theory of paral- 

 lelism has " perhaps not realised 

 all the expectations" which were 

 cherished thirty years ago. 



