iqiqI MILLER—CVCAS media 221 



4. Neither protoxylem nor protophloem was found in the first 

 cortical cylinder. Practically all of the xylem elements are pitted, 

 but scalariform tracheids are occasional. 



5. The secondary phloem of both cylinders is characterized 

 by the great number of suberized bast fibers compared to the 

 number of sieve tubes. 



6. .Vll cortical cylinders are similar in respect to their origin 

 and development and are probably related in their appearance to 

 the alternating periods of rest and activity of the plant. 



7. Unfortunately material was unavailable which would have 

 shown the beginning of differentiation of a cortical cambium. 

 Such a piece taken from the stem apex would have been far enough 

 up to destroy material needed for further research. 



Univkrsity of Chicago 



