44 BOTANICAL GAZETTE [july 



in figs. T and 8, the cells do not develop at the same rate nor do they 

 divide simultaneously. That there is some coordination^ howeyer, 

 is shown by the fact that figures do not usually occur isolated, but 



small groups 



m some 

 mother- 



cell stage. 



come 



same time, ihis seems 



point in the development at which the cells are all at approximately 

 the same stage.. Each cell seems to develop independently of the 

 others in the majority of cases, although there are not lacking fre- 

 quent cases where several cells lying s^de by side are approxii;nately 

 in the same phase. The most striking examples of this, are groups 

 of cells in the late prophase often found among young tetrads or even 

 in sporangia, where the young spores have become separated and 

 have rounded off. Fi2. sives a view of a 



mo 



Sim 



clearness). The cells at this stage are oblong and about 28X32 /*'. 

 The cell shown in the drawing is one of the largest, being 27 X40 /*'. 



very 



from 



one another entirely or into small groups. The walls are so 

 thin that it was sometimes impossible to find them, though it was 

 always possible to find other cells younger, of the same age, and 

 older, which showed the wall, so that it seems likely that all of them 

 really have walls. It has already been noted that Stevens did not 

 find them in B. virginianum at certain stages. Cardiee shows in 

 his figures what seem to be walls, but makes no text comment. Beer 

 is emphatic in his assertion that they are present at all stages in 

 Helminthostachys. Recalling their exceeding thinness and the 



■ 



difficulty of staining them, one must accept with considerable 

 reserve the statement that they are absent at any stage. However, 

 w^hen one considers that most of the walls disappear in the 



seem 



to 



improbable that they may totally disappear in some cases. It may 

 be added that the writer has been able to find them in preparations 

 of B. virginiamim of the same age. The preparations examined do 



that they are always present. 



positiv 



