234 Heredity and Eugenics 



Its larval stages are totally different from the larval stages 

 of signaticollis , and the general appearance of the organism 

 is totally different. This type, derived from these variations 

 by a series of hybrid modifications, if placed side by side with 

 the normal species is so strikingly different that if found in 

 nature no one would hesitate for a moment to designate it 

 a distinct Linnean species. Not one of the characters in 

 this form is new, and each is directly traceable to one or 

 the other of the parents — but the form shows a new arrange- 

 ment of these attributes. 



In this species a germinal modification, obtained through 

 hybridization, resulted, in which a rearrangement of 

 attributes produced new combinations which are stable 

 under the conditions of existence. It cannot be said in 

 this case that anything new has been produced, only that 

 existing characters have been rearranged and produced a 

 combination hitherto unknown. This is the commoner 

 type of modification through hybridization; there are, how- 

 ever, other types of changes which are still more interesting. 



3. BY COMBINED SELECTIVE CONCENTRATION AND 



HYBRIDIZATION 



A good example is found in a series of experiments 

 recently carried out, in which L. undecimlineata was crossed 

 with L. signaticollis of the modified 419 stock, but with 

 these differences. There is a tendency in certain races of 

 L. undecimlineata for the ramous stripe to be broken about 

 one-half its distance from the anterior end. The break in 

 this stripe is fairly common, but is something which is 

 not really fixed in this species, at least by means of any 

 known process; that is, it cannot be rendered a permanent 

 invariable character, but a race can be created in which the 



