miscellaneous: stimuli underlying tumor-formation 517 



Fig. 388. — A. Hyperplasia in a lenticel on a young olive shoot due to treat- 

 ment (March 4, and several times after that) with petrolatum. Response rather 

 slow. From an unstained free-hand section. Photographed March 28, 1918. 

 8 mm. obj., 4 oc, bellows at 45. B. Cross-section showing a normal lenticel. 

 Olive shoot of same age as A. The dark color under the lenticel is due 

 to chlorophyll. 



