138 



REGENERATION 



cortical layers alone, although the rate of growth of both roots and 

 shoots is considerably retarded when part of the wood is removed. 



Fig. 113.- — Proof that shoots can be formed by cortex alone. 



1923. 



Oct. 16 to Nov. 8, 



The basal end of the cortex can also form a callus if it is deprived 

 of the wood, though this callus formation is slight at the best. 

 The experiments lasted from Oct. 16 to Nov. 8, 1923. 



Fig. 114. — Proof that roots can be formed by cortex alone. Oct. 16 to Nov. 8, 



1923. 



For the next experiment stems such as in Fig. 115, a, were used. 

 They possessed three nodes and a pair of large leaves in 

 the middle nodes. A ring of cortex was removed from a piece of 



