CHAPTER VIII 



THE PROBLEMS OF TRANSFORMATION 



WE have now surveyed some of the more important 

 features connected with the transformation of insects. 

 It remains to consider the meaning of these facts. 

 Not infrequently in the course of the preceding chapters has 

 reference been made to the belief, now universally held by 

 naturalists, that besides the changes undergone by every 

 individual in the course of its life-history, there are changes 

 also in the history of races, and that, to quote Darwin's familiar 

 sentence, " community of descent is the bond which is partially 

 revealed to us by our classifications ". It is also very generally 

 supposed that in the life-history of an animal some suggestions 

 may be found as to the course of evolution in the race to which 

 that creature belongs. A question thus arises as to what 

 light the transformations of insects throw upon the develop- 

 ment of the whole class and its various orders through the 

 course of the great periods that mark the progress of life on 

 our earth. 



The transformations of insects present a peculiar problem 1 

 when we compare them with the changes which other animals 

 undergo in the course of their development. Metamorphosis 

 is a feature accompanying growth in many groups of the 

 animal kingdom. We may compare, for example, a bird 

 hatched from the egg, or a puppy or a kitten born, in a form 

 which clearly stamps it as the offspring of its parent, with the 

 infant frog which begins its free life as a fish-like larva, the 

 tadpole, differing from its parents not only in its comparatively 

 undeveloped condition but in such striking outward differences 

 as the absence of limbs and the presence of a tail. Here within 



1 L. C. Miall : " The Transformations of Insects ". Nature, LIII. 

 1895. A. Hyatt and J. M. Arms : " The Meaning of Metamorphosis ". 

 Nat. Sci., VIII. 1896. R. Heymons : " Die verschiedenen Formen der 

 Insectenmetamorphose ", Ergeb u. Fortschr. Zool. I. 1909. 



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