1921] HAUPT—REBOULIA 451 
The protoplasm of the elaters becomes further withdrawn from 
the cell wall, and a double spiral band appears in the form of a 
local thickening on the inside of the elater wall. Finally all of 
the protoplasm is lost, as its substance seems to contribute 
to the further development of the spiral band. 
The relation between the protoplasmic contents of the elaters 
and the formation of their spiral band was studied in all available 
Stages in their development. In no case was a behavior observed 
such as has been described by CAMPBELL (1) for Fimbriaria 
californica: 
The elaters are at first elongated thin-walled cells with a distinct although 
small nucleus, and nearly uniformly granular cytoplasm. As they grow the 
cytoplasm loses this uniform appearance, and a careful examination, especially 
of sections, shows that the granular part of the cytoplasm begins to form a 
spiral band, recalling somewhat the chlorophyll band of Spirogyra. This is 
the beginning of the characteristic spiral thickening of the cell wall, and while 
at first irregular, the arrangement of the granular matter becomes more definite, 
and following the line of this spiral band of granules in the cytoplasm, there is 
formed upon the inner surface of the wall the regular spiral band of the com- 
plete elater. 
The mature elaters average slightly over 1.0 mm. in length, the 
longest one measured being 1.36 mm. and the shortest 0.94 mm. 
The mature spores average 70-80 in diameter. The mature 
sporophyte reaches a length of 1.6-2.0 mm. The capsule is oval 
or slightly obovate; its wall is but 1 cell thick except near the apex, 
where a cap 3 or 4 layers of cells in thickness is formed. The outer 
wall cells develop simple annular and half-ring fibers. Dehiscence 
of the capsule was not observed, but it is probable that the apical 
cap comes off. The seta of the mature sporophyte is comparatively 
very short, and the foot is bulbous, never anchor-like. 
Summary 
1. The embryo of Reboulia develops without the foeantion of 
an octant stage characteristic of certain other Marchantiaceae. 
2. The first transverse wall in the fertilized egg separates the 
cell which is to form the foot from that which is to form the seta 
and capsule. Four horizontally: superimposed cells are usually 
formed, each new division occurring in the outermost segment. Of 
