448 



QUANTITATIVE LAWS IN REGENERATION. m 



the two buds of the most apical node will grow into shoots, while the 

 buds in all the nodes below will remain dormant. Permanent roots 

 will grow only at the base of each piece, though transitorily air roots 



In air 



m 



"= 



y 



Fig. 1. Pieces of stem from the same plant, (1) apical, (2) basal. Suspended 

 in moist air, shoots formed only in the apical node, roots at the base. Mass of 

 shoots and roots is larger in the basal piece (2) which has the larger mass. Dura- 

 tion of experiment October 4 to November 7, 1921. 



In air 



U 



Qti 



^ # 



Fig. 2. Stem cut into small pieces with 1 node each. Suspended in same aqua- 

 rium and simultaneously with large stems in Fig. 1. (1) was the most apical, 

 (9) the most basal piece, the serial number denoting the original position of the 

 pieces in the plant. Each piece of stem forms 2 shoots in its node, but the relative 

 mass of the shoots varies with the relative mass of the stem, not with the serial 

 number of the node. 



may begin to form in any node, but these will dry out as soon as the 

 basal roots are growing.* Fig. 1 illustrates this polar character of 

 regeneration in defoliated pieces of stem suspended in moist air. 

 When, however, a long defoliated stem is cut into as many 



* Loeb, J., /. Gen. Physiol, 1918-19, i, 687. 



