THE VALIDITY OF THE MASS RELATION 



49 



2 or 4 and 5 during the same time and under equal conditions. 

 It may also be pointed out that these large middle pieces (3) 

 formed their basal roots earlier than the small pieces and that 

 the mass of their roots remained greater than the mass of roots 

 in the small pieces (Figs. 40 and 41). 



^. 



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Fig. 40. — Five pieces cut from the stem of the same plant, (1) and (2) apical 

 pieces with 1 node each, (3) middle piece with 6 nodes, and (4) and (5) the basal 

 pieces with 1 node each. The large middle piece produces larger shoots than 

 either the more apical or more basal small pieces. The large middle piece has 

 ample roots while only the longer basal piece commences to form a root. Dura- 

 tion of experiment, Oct. 25 to Nov. 21, 1921. 



It turned out that the shoot production in the most apical 

 pieces of stems 1 and 2 was usually irregular, as a rule too small, 

 so that these pieces were not well usable as controls. The basal 

 pieces 4 and 5, however, behaved normally. It seems that this 

 abnormal behavior of the small apical pieces is found as long 

 as the leaves connected with this piece are still small and growing, 

 and is perhaps due to the fact that the bud from which later 



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