24S Heredity and Eugenics 



in definite areas can be acted upon by selective combinations 

 to produce permanent results. One example will ser\'e to 

 illustrate this. 



Material of L. siiiiiatico/lis Stal, a specific form limited 

 to a narrow habitat in nature, and of low \'ariability in all 

 of its characters, was the basis of this experiment in selec- 

 tion. Compared with other members of the genus with 

 which it is closely related, the variations of L. sifiiiaticollis 

 are trivial, so that one would on a-priori grounds be certain 

 to regard it as a hopeless task to attempt with L. signati- 

 collis studies in experimental evolution by selective methods. 

 By a process of combining variations in the pattern of the 

 pronotum it is possible through a series of generations to 

 create a type of pattern permanent in all respects, and which 

 behaves, when crossed with other patterns, with all the 

 sharp alternativeness of characters found in nature. 



The selection was begun in the ninth generation of the 

 stock which had been bred as group cultures and as pedigree 

 cultures and had never shown the modifications which 

 were produced ; further, the modifications produced are 

 not known to exist in nature. In the P"g generation, a 

 combination was made of the pronotal pattern, and from this 

 there arose a variable progeny, Fio- From generation !",„, 

 matings were made and during generations F,,, P\,, F,^, 

 Fi^, F,5, and F15, etc., the combinations were made from 

 generation to generation, with the end result that there 

 has been developed a j)ermanent strain, which since the 

 F,, of P",, generation has remained stable. In this strain 

 the spots are all fused into one solid mass and are carried 

 backward until they completely border the posterior edge 

 of the i)ronotum, and anteriorly to the anterior edge and 

 laterall}', leaving onl\- a small border unpigmented. Such a 



