EXTRA CHROMOSOMES — BLAKESLEE 



439 



somal diagram of such " B " races is shown in.Fif^ure 4. It will be 

 noted t)iat all except the white and the stippled chromosomes are the 

 same as those in our standard line 1 (Fig. 3). There is no necessary 

 difference between the two races, in respect to the factors which these 



"B" RaCE 



\ 



I 



FiQUBB 4. — Diagram of chromosomes of the " B " race. The 

 stippled chromosomal material is part in the I. chroinosome 

 an'l part In tlie m chrornosomp. In the standard line 1 

 (of figure 3), the stippled material is all In the m chromo- 

 some 



two chromosomes contain. The groupin<T of these factors merely is 

 changed. If its L chromosome were extra in a plant of the " B " 

 race, it would form a primary (2n + l) type of this race. It is con- 

 venient, however, to use our line 1 as a standard and to classify types 



