1918] CRIBBS—MARCHANTIA 95 
Marchantia they sometimes develop so abundantly in the center of 
the capsule as to produce a columella. 
Intermingled with the elaters occurs considerable tissue derived 
from sporogenous cells which undergo elongation and divide fre- 
quently, giving rise to chains of cells. These fail to reach the spore 
mother cell stage, and may persist for a considerable time. They 
either partially or completely disorganize, however, about the time 
the elaters develop their wall thickenings. 
The disintegration of these sporogenous cells is a feature limited 
to the columella, and apparently is not essentially a nutritive 
function, but is a condition arising from the close grouping of the 
central elaters. 
A columella of this type strongly suggests the elaterophore of 
Pellia, and is an advancement in the organization of the sterile 
tissues of this family along the same line of development that regu- 
larly appears in members of the Anacrogynae. 
That this unusual occurrence may be attributable directly to 
external factors is highly improbable; but should be considered 
the first stage in the tendency to break up the sporogenous mass, 
a feature very prominently displayed in the sporophyte as it 
increases in size and complexity. 
The initial separation of sterile cells at the apex may occur even 
before the intrusion of the proximal part to form the foot, or it 
may first be recognized at the time of the initial elongation of the 
Sporogenous cells. 
The group of cells thus separated at the tip may be added to 
either by the division of the wall cells, or by periclinal walls in the 
elongating sporogenous cells. 
This occurrence of a cap of sterile cells at the apex of the capsule 
is likewise a feature appearing prominently in members of the 
Anacrogynae, where in Ameura it bears attached elaters. The 
occasional appearance of three or four layers of sterile cells at the 
tip, and the convergence of the elaters, together with the close rela- 
tion they frequently bear to this point, are further evidences of 
transitional features from the diffuse arrangement of elaters to a 
definite organized structure such as the elaterophore found in 
members of the Jungermanniales. 
