5°4 



BOTANICAL GAZETTE 



[DECEMBER 



a week or ten days small swellings (adventitious buds) appeared 

 on the hypocotyl. It is found, upon studying longitudinal sections 

 of these hypocotyls, that the meristem of the bud is composed of 

 small cubical cells which have arisen, by division, from the epidermis 

 and outer cortical cells. Deeper cortical cells, however, are found 

 to be elongating and apparently dividing parallel to their long 

 axes, that is, in the direction of the current of food materials pass- 

 ing to the growing meristem 



It is well known that 

 Haberlandt (15) correlates 

 the shape of the palisade cells 

 with the transportation of 

 the products of photo- 

 synthesis. A similar elonga- 

 tion of cells for the purpose 

 of conduction is found in the 

 secondary transfusion tissue 

 of Cycas, where, according to 

 Worsdell (38), the ordinary 

 mesophyll cells become modi- 

 fied in order to supply water 

 to the parts of the leaf which 

 are distant from the bundle. 

 From Goebel's study of 



Fig. 6.—Scirpus validus: cross-section of adventitious buds (14) »t IS 

 older stem: p, partition cells; d, diaphragm seen that the bundle becomes 



cdfa perpendicular to the partition; i\ cells differentiated first in the leaf 



not in position characteristic of cells adjoin- 

 ing partitions; X175. 



and afterward extends itself 

 backward, until it reaches 



and becomes connected with a bundle 



in 



the stem. This 



elongation of cells to continue the bundle may be interpreted as a 

 result of the current of food materials passing to and from the 

 growing leaf. In a similar way the current of food materials 

 from the cross-bundle to the partition walls of the air space may 

 determine the direction of the walk of the around of rells in the 



r a trm s 



