542 



The Journal of Heredity 



SPOTTED VARIEGATION IN A BEGONIA 



Not a chimera, but a plant probably suffering from infectious chlorosis. Its ofTspring, if pro- 

 duced by seed, will be normal; while if it were a periclinal chimera, as it appears at first 

 sight, its parti-colored conditifjn would be inherited. The spots on the leaves here start 

 from time to time at a distance from the large veins and spread until they fuse together. 

 The nature of the disease is not yet altogether clear to scientists. (Fig. 14.) 



producirifj a small percentage of green 

 plants should be considered a homozy- 

 gf)te in the strict sense of the word. 



Baur's (8) "variegata" type of snajj- 

 dragon differs from this in the fact that 

 it is true to seed, no green i)lants being 

 produced. Normal green is dominant 

 to this type of "variegata" and both 

 arc dominant to "chlorina." The F2 

 generation splits in each case in the 

 common 3 : 1 ratif>. Baur's cx[)lanation 

 is V)riefly this: 



1. A factor. A, makes the green sjjots 

 of "variegata" possible even in the al)- 

 sence of a second factor B. 



2. A factor, B, makes a uniform green 

 color possible even in the absence of 

 factor A. 



Then aaBB arc green plants true to 

 seed. 



AA1)1) arc "variegata" plants true to 

 seed. 



aabb arc "chlorina" i)lants true to 

 seed. 



This theory agrees with the facts 

 except for the cross between green and 

 "variegata" in which the Fi plants 

 would be AaBb. They should then 

 fonn germ cells with tlie factors AB, 

 Ab, aB and al) in eciual ntnnbers and 



