Studies of Teratological Phenomena. 125 



of their branches. And of these plants, some may be homozygous in 

 enough of the factors which transmit the branching habit, that a constant 

 race could be obtained. Again, under X2 genotj^ical environment, the 

 factor A may not be able to express itself at all in the stem, and the 

 abnormal floral and phyllotaxy contlitions may be reduced, owing to the 



Fig. 27. Fj types of stems resulting from crossing the fasciated 

 race -with normal-stemmed races of N. tahacmn. 



presence of modifying factors in this gene complex X->, that were absent 

 in that of Xi. Hence among the F. progeny of crosses 353X301, 

 396 X 301, etc., plants segregated out wliich, judged by the expression 

 of the factor A under Xi conditions, would be recorded as heterozygotes, 

 yet they may be just as truly AA segregates, as any AA plants could 

 be. Such a state of affairs causes extreme confusion in a study of 



