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animals wliich are entirely independent i)f one another. The conclusions based 

 upon the facts of anatomical and morphological research must always give way to 

 the direct proofs of biology. The significance of corporeal characters is established 

 by biology. Anatomy and morjjhology give the quantity, biology determines 

 the quality. It is therefore obvious that the classifier should not let himself 

 be guided in his judgment solely by a consideration of the quantity of bodily 

 characters, bnt always keep in mind the higher criticism of quality. If he does 

 this, he will not easily fall into the error of treating two groups of individuals 

 as being of the same classificatory category (variety, species, genus, etc.), if 

 biological considerations are against it. If the classifier had no other guide 

 than corporeal similarities and differences, the classification would merely be an 

 artificial arrangement, without regard to the true connection between the animals 

 classified. Such a classification, perhaps very useful for the mere collector, 

 might be likened to an arrangement of minerals according to their external 

 features, without any regard to their chemical composition. 



Although there are no biological data available of most animals, of which 

 we know nothing but what the dead bodies or portions of them (embryo to 

 adult) tell us, the scientific classifier has nevertheless another guide. Tiiis 

 guide is the principle of judging from analogy (the word used in the logical 

 sense). We give two illustrations. If in a certaiu country the spring- and 

 summer-broods of a certaiu grouj) of species have been proved to be different 

 in all the species examined, we may safely conclude that they differ also iu 

 those species of the group which have not yet been examined. Therefore, forms 

 of that group of which it is only known that they differ iu the same way 

 as the horodimorphic forms of the better-known species must also be treated as 

 seasonal varieties, and not as distinct species. As we have found that the 

 genital armature, though individually variable, does not exhibit any seasonal 

 differences in those species of Lej)idoptera of which forms proved to be seasonal 

 have been examined by us, we are bound to conclude that Lepidoptera which 

 do constantly show differences iu those structures are not seasonal forms of one 

 species. The j)remiss is the better established, and hence the conclusiou is the 

 more likely to be correct, the more species have been examined. This deductive 

 reasoning, though logically exact, will never give us certainty. For the animals 

 as we know them are the product of evolution ; the result of evolution is 

 dependent on the nature of the animal and of the evolving extraneous factors ; 

 these extraneous factors being independent of the animal, their combination 

 with the internal factors — which combination dete-mines the line of develop- 

 meut— depends on accident ; results determined by accident canudt be deduced 

 from an a priori law. That means, we do not a priori know that what holds 

 good in all the cases examined is true also in every case not yet examined. 

 Nearly all the so-called " laws " in biology are nothing but more or less well- 

 formulated rules of probability admitting of exceptions. A rule may apply to 

 every individual case within a certain group of animals ; but the further away 

 we go from that group, the greater becomes the chance of exceptious turning 



