THE VALIDITY OF THE MASS RELATION 



45 



not only the 2 buds in the most apical node of a long piece of stem 

 grow out but also 1 or 2 buds of the node below (Fig. 37). The 

 rate of growth of shoots and roots is also greater in the stems put 

 with their base in water (Fig. 37) than when the stems 

 are suspended in moist air (Fig. 35). When pieces of stem with 

 only 1 node each are put into water each piece forms shoots at 

 its node (Fig. 38). 



By comparing the amount of shoots formed simultaneously in 

 the one-node pieces in Fig. 36 or 38 and in the four-node pieces 

 in Fig. 35 or 37 the reader will notice that the shoots are greater 

 in the larger pieces of stem, and the same fact can be observed in 



Fig. 38. — Stem of one plant cut into 10 small pieces, the serial number indi- 

 cating their position in the plant, (1) being the most apical, (10) the most basal 

 piece. Base in water. Experiment simultaneous with that represented in 

 Fig. 37. Each piece has formed 2 shoots, the relative size of which does not 

 follow the serial number of the stem, but the relative mass of the stem. The 

 size of each shoot of the pieces is much smaller than the size of the shoots formed 

 simultaneously by the larger stems in Fig. 37. The latter stems all have roots, 

 while only the two largest pieces of stems (6) and (10) in Fig. 38 have formed 

 them. 



all the other figures in this chapter. It is almost obvious from a 

 glance at the figures that the mass of shoots formed increases 

 with the mass of the stem. It is intended to show that within 

 the limits of the experimental errors, the mass of dry weight of 

 shoots produced per gram of dry weight of stem under the same 

 conditions and in the same time is about the same, regardless of 

 whether the stems are long or whether they are subdivided into 

 one-node pieces. 



The defoliated stem of a very large plant was cut into 5 

 pieces, each possessing 4 nodes (Fig. 37), and the defoliated stem 

 of a second plant was cut into 10 small pieces of 1 node each (Fig. 

 38). The pieces dipped with their base into water and the large 

 and small pieces were suspended in the same aquarium. The 

 experiment lasted from Sept. 27 to Oct. 22, 1922. The shoots 

 were then cut off and both shoots and stems were dried for 24 



