THE CROWN gall: CAUSE 



431 



Fig. 329. — Crown gall confined to the bark parenchyma of a Paris daisj^ 

 stem but containing tracheids (above X), induced by needle inoculations }i mm. 

 deep. Under and at the left of X there is action at a distance, i.e., large cells 

 like X are dividing as if by a stimulus received from the neighboring hyperplasia. 

 The same phenomenon has been observed in crown gall on tobacco. (Consult 

 Jour. Cancer Research, Vol. I, No. 2, Plate I, Fig. 3, and Plate XXIII, Fig. 78.) 



