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the conception of species has ceased to express a natural phenomenon ; in 

 contemporary science it has only a systematic meaning. Now it is obviously 

 unscientific to try to find natural characteristics for something that is not a 

 natural phenomenon. The development of new forms out of already existing 

 ones, is a phenomenon of evolutionary change; to be able to answer the 

 question of whether a new form shall be acknowledged as a new species, 

 systematically, it is essential to know how far this change has proceeded, and 

 in order to be able to judge of this, it is necessary to be familiar with the 

 nature of the evolutionary process and the way in which it acts. This demands 

 scientific study; theories about the specific characteristic which are not based 

 upon this study, are fantastic, not scientific. It is, once for all, impossible to 

 learn to read without first taking the trouble to learn your letters and even to spell. 

 It is true, that when a species is so far differentiated, that it is conspicuously 

 unlike all others, this difference can usually be traced in the construction of its 

 internal organs, in which case it can be used as distinguishing characteristic. 

 But when the differentiation has not yet become so marked, experience shows 

 that it proceeds ver)^ unevenly with regard to all the external organs. Thus, 

 although in some respects important differences from the original species may 

 have developed, all the rest may have remained the same. And seeing that 

 this irregularity in the rate of progress is characteristic of every evolutionary 

 process, it is not easy to believe, that the internal organs should form an 

 exception. So that, where with regard to these a considerable differentiation from 

 the original species may have taken place in some respects, it does not neces- 

 sarily follow, that it will be so with all the organs; some may have remained 

 the same as in the original species; while in other cases it will be just these 

 organs that have the first entered upon differentiation. Therefore the systematic 

 arrangement of species cannot be based upon this. This fact is incomprehensible 

 to those who entertain a one-sided prejudiced point of view and are ignorant 

 of the fact, that the organisms are subject to an evolutionary change which at 

 certain periods is very active in some species. This is the reason why, when 

 research showed, that the ancient form Hilaria Cram did not coincide with 

 the common form of Callidryas Pomona F. as regards the genitals, and that 

 the genitals of the old form Blanda Bsd. are not the same as those of the 

 common kind Terias Hecabe L., it was erroneously concluded that Hilaria Cram 

 and Blanda Bsd. must be separate species, although breeding had demonstrated 

 the contrary. Of the first form there only exist cf, as a matter of fact, similarly 

 as in the old 9 forms Achates L. of Papilio Memnon L. and Zithenius Herbst 

 of Cyllo Leda L. there are only $. It is the same with the genitals of the 

 Lycaenidae. These are also subject to evolutionary change, and as it would 



