JACQUES LOEB 



711 



latter roots will soon surpass in mass the apical roots, the apical roots 

 will not wilt. The basal roots, when they develop in air instead of in 

 water, do not grow rapidly enough to suppress the growth of the 

 more apically situated roots. The drawing was made on the 30th day 

 after the beginning of the experiment. The upper half of the stems 

 had been cut off in this experiment. If, however, the leaf is not at 

 the base but in the middle of the stem, as in Fig, 22, roots will 



Fig. 22. Leaf in middle of stems suspended horizontally. Practically no roots 

 develop in front of the leaf, the nodes basaUy from the leaf inhibiting the growth 

 in the more apical nodes. Drawn after 24 days. 



develop and persist only basally from the leaf. It is only necessary 

 for this result that one node is preserved basally from the leaf, as 

 in Fig. 23. 



When we suspend a stem of Bryophyllum calycinum, possessing one 

 leaf in the middle and on the under side of the stem, horizontally in 

 moist air, the root formation will usually start first from the second 



