94 GENETIC VARIATIONS 



'^'^ Page 84. Among the so-called mutations of De Vries it has been the 

 custom to distinguish certain ones as actual "gene mutations," while 

 the rest are but rearrangements of chromosomes or parts of chromo- 

 somes. If the theory of position effects is substantiated, these "gene 

 mutations" are likewise only rearrangements of parts of chromosomes. 

 ^^ Page 84. This relation of the "position effects" to evolution is recog- 

 nized by MuUer and his associates. In the first publication giving an 

 account of the relation of the scute mutations to the change of position 

 of the zones on the salivary chromosome, Muller, Prokofyeva and 

 Raffel (see Note 10 above) close with the following remarks: 



"These and other cases raise the question: Are most, perhaps practi- 

 cally all, X-ray 'gene mutations' intergenic position effects rather than 

 intragenic transformations? And the more momentous question fol- 

 lows: To what extent may natural mutations be of this type — a type 

 incapable of providing the material for indefinitely continued 

 evolution?" 



" Page 87. See H. F. Osborn, "Aristogenesis, the Creative Principle in 

 the Origin of Species," The American Naturalist, 1934, Vol. 68, pp. 

 193-233; and other references there given. 



" Page 89. See F. B. Sumner, "Genetic, Distributional and Evolution- 

 ary Studies of the Subspecies of Deer Mice (Peromyscus)," Bibliog- 

 raphia Genetica, 1932, Vol. 9, pp. 1-106; also, "Taxonomic Distinctions 

 Viewed in the Light of Genetics," The American Naturalist, 1934, 

 Vol. 68, pp. 137-49. 



