CHAPTER V. 



PRODUCTION IN EXPERIMENT OF RACES, NEW CHARACTERS, AND SPECIES 



IN LEPTINOTARSA. 



The species of Leptinotarsa are clearly and distinctly separated from one 

 another, and each has its particular groups of characters. This isolation, or 

 lack of continuity, exists everywhere among all the species, when taken as a 

 whole, and also in their particular attributes ; and even though species possess 

 the same character in common, or the characters overlap, each in its totality 

 of characters is distinct from the sum total of characteristics discoverable in 

 its most immediate relative. 



According to the Darwinian hypothesis this distinctness of species is sup- 

 posed to be the result of the extinction of intermediate forms ; however, few 

 traces of such a process have as yet been certainly demonstrated. In plants, 

 De Vries has described elemental species separated from one another by lesser 

 magnitudes than those separating species. The further extension of this idea 

 and its investigation in CBnothera has shown that in plants elementary species 

 arise by sudden development, so that the new is always separated from the old 

 by definite characteristics. This sudden permanent change of form is a phe- 

 nomenon more or less well known to plant and animal breeders, and has been 

 the means through which many of our domesticated animals and cultivated 

 plants are supposed to have arisen ; but it was until recently considered to be 

 a process peculiar to domesticated races, and the Darwinian idea of slow isola- 

 tion as the result of extinction was the generally accepted hypothetical process 

 in nature. The work of De Vries, however, shows conclusively that in plants 

 the rapid development of new forms takes place also in nature, and it is now 

 an established fact that it is not confined to domesticated races, but is common 

 to both wild and cultivated plants. Among animals, however, the state of our 

 information is far less satisfactory, and it is decidedly an open question as to 

 whether the origin of species in animals has been by slow modification and 

 extinction, rapid transmutation, or by "mutation." 



The attack upon this problem in animals is far more difficult than in plants, 

 the obstacles to be overcome and the apparatus and expense demanded being 

 so excessive that but poor headway will be made as compared with that of 

 the plant evolutionist. Moreover, the problem is more complex in animals 

 than in plants, and the ramifications, whose solutions are necessary before 

 we can arrive at a really safe hypothesis, are numerous. The attack must 

 be made from two sources : First, from careful observation in nature of the 

 material under investigation, that the observer may become thoroughly 



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