METHODS 



arise the slender, apparently adventitious branches which are often met 

 with upon the ventral side of the shoots. These slender cylindrical root- 

 like branches may be only a few cells in thickness, and are traversed by a 

 conspicuous strand of conducting tissue, which can easily be traced to 

 the base of the shoot, where it ends abruptly, and does not join the cor- 

 responding strand of the main axis. The occurrence of ventral branches 

 is confined mainly to the prostrate portion of a shoot, or to the base of the 

 stalk of the frond. They may, however, occasionally arise from the ven- 

 tral side of the expanded portion of a frond, and in the only case 

 observed (Fig. 2, G) the shoot was much broader than those arising from 

 the stalk of the frond or from the prostrate rhizome. The frond from 

 which this shoot arose bore empty antheridia. 



The apical cell of P. decipiens, a species from Ceylon, strongly re- 

 sembling P. Zollingeri in general appearance, has been carefully studied 



A. , 3 



A. Vertical section of the growing point of a frond segment of Pallavicinia Zollin- 



geri. 



B. Horizontal section of the same, x, primary apical cell ; x' ', secondary apical cell. 



C. Cross-section of the conducting strand from the stalk of the frond of Pallavi- 



cinia Zollingeri. 

 Some of the conducting cells, more highly magnified. 



E. Longitudinal section of conducting cells. 



