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University of California Puhlications in Botany [Vol. 5 



with an asterisk. Strangely enough, it was one of the two in the table 

 which did not throw hose-in-hose flowers. The other normal selections 

 all threw hose-in-hose flowering plants in the proportion of about 3 

 normal to 1 hose-in-hose. 



In subsequent generations only the three families which were pre- 

 viously considered under flower color were grown. Normal flower 

 selections from 12¥ Jl^^ ^r^ ^^ gave two populations, one of 100 and one 

 of 97 plants. The plants all bore normal flowers. In ISF^HisPasPuPi., 

 it was noted that some flowers were split, but there was not even a 

 suggestion of approach to the true hose-in-hose condition. The other 

 population ISF^HooPoePsPs was from a hose-in-hose selection in the 



TABLE 15 



Fs BEHAVIOR OF TALL SEGREGANTS. 



corresponding F3 population. Ninety-four plants were grown to ma- 

 turity, all of which were strictly hose-in-hose. In subsequent gener- 

 ations these three populations bred true to type save for the sporadic 

 appearance of hose-in-hose flowers on plants which otherwise bore 

 nothing but normal flowers. This, however, is not an unusual phe- 

 nomenon even in pure line cultures of normal flowering varieties of 

 Tdbacum, and it is extremely doubtful whether the hybrid derivation 

 of these plants had anything to do with the production of occasional 

 split flowers. 



As respects height of plants the F3 data are given in tables 15, 16, 

 and 17, which give the behavior of tall, medium, and short F2 segre- 

 gants respectively. The behavior here is not very convincing. Prob- 

 ably the difficulty in judging the character and the influence of 

 variation in soil condition had something to do with it. 



