106 



REGENERATION 



Fig. 82. — Similar experiments as in Fig. 81, except that stems and leaves are 

 suspended horizontally in moist air: I, with whole leaf, forms a larger shoot at 

 apex than II, with a leaf reduced in size; III, without leaf, produces only tiny 

 shoots. Notice also that geotropic curvature of stem increases with mass of leaf. 

 Apr. 3 to 21, 1923. 



Fig. 83.— a stem partially split. The sap from the apical leaf had to cross over 

 to the other side of the stem and inhibited the shoot formation on this side. 

 Then the sap had to cross over again at the base, giving rise to a shoot. The 

 mass of these shoots was greater in stems with leaf attached than the mass of 

 shoots in stems without leaves. Jan. 9 to Mar. 16, 1923. 



