352 



PHYSIOLOGICAL BASIS OF POLARITY. I 



developed on the lower side in the second node. In the five stems on 

 the right the mass of the leaf was reduced considerably. Four of the 

 five stems formed shoots, two even in the second node on the upper 

 side of the stem. In a repetition of this experiment half of the stems 

 with a reduced apical leaf on the upper side formed shoots in the 

 first node basally from the leaf. 



Fig. 14. Horizontally suspended stems. Leaf on upper side. The lower half 

 of stem is removed with exception of second node. The lower bud of the sec- 

 ond node grows out into a shoot, while the shoot formation on the upper side 

 of the stem is inhibited by the leaf. Duration of experiment, Feb. 13 to June 24. 



The reader will notice that the geotropic bending of the stems was 

 considerably less in the five stems on the right with the reduced leaf 

 than in the five stems on the left with a whole leaf.^ 



^Loeb, Science, 1917, xlvi, 115; Ann. Inst. Pasteur, 1918, xxxii, 1; Forced 

 movements, tropisms, and animal conduct, Monographs on Experimental Bi- 

 ology, Philadelphia, 1918. 



