14 



Problems, Concepts and Their History 



plasm and of cells when von Kolliker and 

 Remak and others brovight together the re- 

 sults of these with the results of the germ 

 layer doctrine. Had these continued as the 

 main trends of embryology, von Baer's syn- 

 thetic scheme would have been broadened 

 in the fashion it deserved. Instead, a return 

 to the overgeneralization of Naturphiloso- 

 phie once more delayed its progress into the 

 future. 



One symptom of this was the continued 

 emphasis, in spite of von Baer's warnings, 

 on the comparability of embryos of "higher" 

 forms to the adults of "lower," and such false 

 analogy was carried over even into the germ 

 layers, von Baer's own territory, thus seem- 

 ing to be supported by his facts though he 

 had so explicitly denied the concept. Hvixley, 

 in 1849 (p. 426), described the Medusae as 

 constructed of two membranes "which ap- 

 pear to bear the same physiological relation 

 to one another as do the serous and mucous 

 layer of the germ," opening the way for the 

 viltimate generalization. When, therefore, 

 shortly after the publication of the Origin of 

 Species, Kowalewski found that invertebrate 

 and vertebrate embryos alike formed from 

 a bilaminar sac, that in the most varied 

 material — Psolinus, Amphioxvis, Phoronis, 

 Limnaeus, Ophiura, Echinus, Asteracanthion, 

 Sagitta, Ascidia, Escholtzia, Sepiola as well 

 as birds, mammals and turtles — 



. . . bei alien von mir hier erwahnten Embryonen 

 geht die Bildung der beiden erwahnten Schichten 

 oder Blatter (der ausseren und inneren) ganz auf 

 dieselbe Weise vor sich. . . . Also ware die erste 

 Bildung des Embryo fiir alle diese verschiedenen 

 Thiere ganz iibereinstimmend; nur in den weiteren 

 Veranderungen sehen wir die Unterschiede auftre- 

 ten, welche jeden einzelnen Typus bezeichnen 

 (1867, p. 5), 



the decision was sealed. He ended on the 

 same note of caution as von Baer, but his 

 voice too was drowned out by the clamor 

 originating from a new cry of transcenden- 

 talism that surpassed anything the earlier 

 Naturphilosophen would have dreamed pos- 

 sible. The difference, of course, was that 

 meantime the Origin of Species had ap- 

 peared. 



The compulsion to synthesize all of ani- 

 mate nature into a single grandiose scheme 

 which the false analogies of the earlier tran- 

 scendentalism had formerly satisfied was now 

 to be assuaged by the evolution doctrine, 

 which represented a synthesis on another 

 basis; in the new scheme, common descent 

 replaced the archetype as the primary syn- 

 thesizing factor. 



It has been said that it was Darwin who 

 "dragged [organisms] down from . . . meta- 

 physical regions into daily life, and ex- 

 amined their immediate purpose in relation 

 to the whole environment of the living or- 

 ganism" (Radl, '30, p. 381). But Darwin in 

 some ways advanced no more abruptly in 

 respect to the descent from metaphysics 

 than had von Baer, and the structure of 

 thought he created was in many ways as 

 metaphysical as that of his predecessors. The 

 influence of the environment alone was no 

 new concept; philosophy had been worrying 

 about this problem at least since the time 

 of Leibniz. The species concept, from which 

 Darwin started, was so highly metaphysical 

 that even now the term defies adequate 

 biological definition. Darwin's system was a 

 metaphysical one, too, in that his concern 

 for the individvial organism was subordinate 

 to his interest in the interdependence of or- 

 ganisms; his clue to the nature of their re- 

 lationships came equally from the organisms 

 themselves and from wider areas of thought: 

 from generalizations invented for the fields 

 of geology and economics, and indeed, in a 

 way from his whole century's mood for 

 "Progress." 



One of the primary contributions of Dar- 

 win, however — indeed of all those concerned 

 with the new doctrine of evolution: Buff on, 

 Erasmus Darwin, Lamarck, John Hunter, 

 Wallace and the many others — was the re- 

 focussing once more of attention on the or- 

 ganism as a whole. The key to evolution 

 had come from consideration of the whole 

 living animal, not its parts; evolution was 

 inferred from natural history, not deduced 

 from the preparations in the cabinets of the 

 anatomists where the evidence had been 

 awaiting for centviries the interpretations 

 which the fixity and the tenacity of the no- 

 tions of unity of type had excluded from 

 coming into being. 



It is one of the more curious ironies of 

 history that while before Darwin, transcen- 

 dentalism had closed the minds of investiga- 

 tors to the possibility of explanation of re- 

 semblances between parts of organisms and 

 between whole organisms on the basis of 

 common descent, yet after him the combina- 

 tion of the doctrines was to lead to extremes 

 of exaggeration that were attained sepa- 

 rately by neither. There were many who 

 were to contribute to this: Kleinenberg in 

 Germany and Lankester in England made 

 an early start by relating phylogeny to 

 ontogeny on the basis of comparability of 

 the germ layers (for fuller treatment see 



