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completely altered by accommodation that it 

 is scarcely possible for us to determine to 

 which order of insects this strange creature 

 belongs. In other cases (ffcrmytomyia) the 

 whole development of the individual is modi 

 fied in such a way that it resembles that of a 

 viviparous mammal rather than that of a fly." 

 Father Wasmann here calls attention to the 

 modification in what he calls "the characteris 

 tic marks" of species and also to changes in 

 their physical development. Now it must be 

 observed that among the lower forms of life 

 the divisions of genus and species are not al 

 ways very clearly defined. Indeed what dis 

 tinctions we have here are the factitious divis 

 ions of naturalists, and seldom do any two 

 agree in their classifications. The family lines 

 are not easily distinguished ; very often the 

 lines between orders and classes are not so 

 sharply outlined. Linnaeus, the father of 

 classification, misled by "characteristic marks," 

 actually classed an homopterous insect as a 

 moth. The numerous instances of dimorphism, 

 trimorphism and polymorphism in individuals 

 of the same species both in plants and animals, 



