406 BOTANICAL GAZETTE [November 



From the nature of the dolabrate apical cell there cannot be 

 true dichotomy, if by the term "true dichotomy" is meant the 

 division of the apical cell into two segments alike in shape and size 

 and also like the original apical cell. This seems to be the only 

 standard for the determination of true dichotomy; but frequently 

 the organization of the apical cell of the branch occurs so close to 

 the apical cell of the main branch that the mature thallus has the 



- 



appearance of true dichotomy. In the liverworts which have a 

 wedge-shaped apical cell true dichotomy is the probable form of 

 branching; for a cell of this form can be divided into two cells 



like 



may 



ize a new apical cell. 



Two-celled mucilage hairs are organized from segments close to 

 the apical cell, and these occur on both the dorsal and the ventral 

 sides. These 



m 



formed 



from 



the apex. 



more 



this 



statement seems to be true also for S. aspera. The muci 



formed only in the immediate 



aspera 



common. Leitgeb discusses rather extensively the situation, and 

 traces the branches close to the apical cell. 



Sex organs 



phy 



ma 



ARCHEGONIA 



The archegonia are borne in groups in the dorsal side of the 

 thallus. Each group is surrounded by a deeply dissected involucre, 

 which, is attached on one side to the thallus. Usually there is a 

 group at the place of forking of the thallus, but they are not re- 

 stricted to that region, and often there are several groups close 

 together on one branch. . The archegonia have their origin close 



