io A History of Botany, 1860-1900 



researches and theories of Unger and Naegeli were co- 

 operating to direct the current of thought towards an 

 evolutionary process capable of recognition in anatomy. 

 The study of the ancient forms of plants was not without 

 its influence on the same idea. Researches on fossil plants 

 had not then reached a very advanced state of develop- 

 ment, but even at that early period in their investigation 

 the results obtained led Unger to make a definite pro- 

 nouncement against the constancy of species and in favour 

 of the view of evolutionary development. Naegeli gave 

 the support of his opinion to the same idea, based upon 

 similar considerations. 



While these ideas were slowly and from several points 

 of departure making their way into the stream of scientific 

 thought, the position of the systematists, under the in- 

 fluence of the doctrine of the constancy of species, was 

 becoming continually more hopeless and their outlook less 

 cheerful. Their position was very clearly stated by 

 Bentham in the following words : ' There were no means 

 of estimating the importance or value of characters except 

 by such vague standards as the number of species in 

 which they had been observed to prevail, no means of 

 determining what degree of variation and persistence 

 actually distinguished the species from the variety. The 

 botanist who affirmed that Rubus fruticosus, Draba verna, 

 or Sphagnum palustre were each one very variable species, 

 and he who maintained that they were collective names 

 for nearly 400, for at least 200, or for some twenty separately 

 created and invariably propagated species, had each 

 arguments in their favour to which no definite reply could 

 be given, and systematic botany was in too many cases 

 beginning to merit the reproach of German physiologists, 

 that it was degenerating into an arbitrary multiplication 

 and cataloguing of names and specimens of use to collectors 

 only, and serving as impediments instead of aids to the 



