708 PHYSIOLOGICAL BASIS OF POLARITY. II 



the stem inhibited the further growth of the roots in the more apical 

 nodes of the stem ; in the same way as the more rapid growth of the 

 most apical buds of a stem suppresses in general the growth of buds 

 situated more basally. Thus in each stem (Fig. 17) not only the 



Fig. 20. Short stems with large basal leaves dipping with their apical ends in 

 water. All the stems produced air roots at the basal end, which in this case is 

 above and in air. The lower one of the four stems formed roots at its apical 

 end and these roots dipping in water grew more rapidly than the air roots. In 

 this case the air roots at the upper (basal) end of the stem dried out. Drawn 

 after 26 days. 



most apical buds but also the buds in one or two nodes below began to 

 grow out, but their growth was suppressed by the more rapid growth 

 of the most apical bud (Fig. 18). Fig. 19 is a drawing of the same 

 stems 9 days later. Hardly any trace of the air roots in the upper 



