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QUANTITATIVE LAWS IN REGENERATION. HI 



question is, Why do only the most apical buds of a long defoliated 

 stem grow out? Bonnet had suggested that the ascending sap of a 

 plant was shoot-producing and the descending sap was root-produc- 

 ing. Sachs pointed out that when a piece of stem was cut out from 

 a plant the ascending sap was blocked at the apex and that hence the 

 shoot-producing substances must collect at that end of the stem giv- 

 ing rise to shoots at the apical node; while the descending sap is 

 blocked at the base, giving rise to root formation at that end. 



The problem then exists to prove or disprove the old suggestion of 

 Bonnet and Sachs. The formation of shoots or roots is a synthetic 

 process or a series of catenated synthetic processes, in which soluble 



Fig. 4. Stem of one plant cut into ten small pieces, the serial number indicating 

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

 Base in water. Experiment simultaneous with Experiment III. Each piece 

 has formed 2 shoots the relative size of which does not foUow the serial number 

 of the stem, but the relative size. 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. 3. The latter stems all have roots, while only the two largest pieces of stems 

 (6) and (10) in Fig. 4 have formed roots. 



materials, such as sugars, amino-acids, and other substances, are 

 synthetized into the larger molecules of proteins, compounds of the 

 cellulose type, and others. If the theory of Bonnet and Sachs is 

 correct, it must be possible to show that the two shoots formed at 

 the apex of a long defoHated piece of stem have, within the Hmits 

 of the accuracy of the experiments, approximately the same dry weight 

 as the dry weight of all the shoots would have amounted to if the stem 

 had been cut into as many small pieces as it contained nodes. 



By comparing the amount of shoots formed in the one-node pieces 

 in Fig. 2 or 4 with those of the four-node pieces in Fig. 1 or 3, the 

 reader will notice that the shoots are greater in the larger pieces of 



