CHAPTER XV 



KAKIA" THEORIES ON THE ORIGIN OF VERTEBRATES 



HAKCKKL and Gegenbaur set the fashion for ptiylogenetic 

 speculation, and up to the middle 'eighties, when the voice 

 of the sceptics began to make itself heard, the chief 

 concern of the younger morphologists was the construction 

 of genealogical trees. The period from about 1865 to 1885 

 might well be called the second speculative or transcendental 

 period of morphology, differing only from the first period of 

 transcendentalism by the greater bulk of its positive 

 achievement. It must be remembered that the later 

 workers (at least towards the end of this period) had 

 immense advantages over their predecessors in the matter 

 of equipment and technique ; they possessed well-fitted 

 laboratories in the university towns and by the sea ; 

 they had at their command perfected microscopes and 

 microtomes ; while the whole new technique of micro- 

 scopical anatomy with its endless variety of stains and 

 reagents made it possible for the tyro to confirm in a day 

 what von Baer and Miiller had taken weeks of painful 

 endeavour to discover. 1 But the democratisation of 

 morphology which followed upon the facilitation of its 

 means of research left an evil heritage of detailed and 

 unintelligent work to counterbalance the very great and real 

 advances which technical improvements alone rendered 

 possible. 



This period of rapid development, which set in soon 

 after the coming of evolution and multiplied the concrete 



1 The stages in the development of microscopical technique are well 

 summarised by R. lUirckhardt, (.Icsihichtc tier /.oolo^ie, p. 121, Leipx.ig 

 1907. 



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