EMBRYOGENY AND SPOROGENESIS IN REBOULIA 
HEMISPHAERICA 
ARTHUR W. Haupt 
(WITH PLATE XXXIII AND ELEVEN FIGURES) 
The present paper is a continuation of the writer’s earlier 
morphological study of Reboulia (5). The systematic position of 
the genus and its phylogenetic relationships, as revealed by the 
structure and development of the gametophyte and sex organs, has 
already been discussed. To determine the affinities of Reboulia 
to other Marchantiaceae, as shown by the development of its 
sporophyte, was the purpose for which the present investigation 
was undertaken. 
Material 
Material furnished by Dr. W. J. G. Lanp for the earlier study, 
and collected by him at Rome, Indiana, served to illustrate a 
number of stages in the embryogeny. Most of the material, 
however, was collected by the writer during the autumn of 1919 and 
the spring of 1920 in the vicinity of Hamilton, Hancock County, 
Illinois. In this locality Reboulia occurs in abundance beneath 
moist ledges of sandstone. Material was also obtained from the 
region about Dakota, Illinois, through the kindness of Mr. Eart L. 
LAMBERT. 
Embryo : 
The first division of the fertilized egg of Reboulia is invariably 
accompanied by a transverse wall (figs. 1, 2), the two segments 
being approximately equal in size. From a careful study of later 
stages the conclusion is reached that the epibasal segment gives rise 
to both the seta and capsule, while the hypobasal segment forms the 
foot. Ina recent preliminary paper on Reboulia, WoopBURN (8) is in 
agreement with this interpretation. The next division results in 
the formation of a transverse wall in the epibasal cell which differ- 
entiates the cells which are to form the seta and capsule (fig. 3) 
A tier of 3 horizontally superimposed cells is thus developed. The 
lowest cell may again divide by a vertical wall (fig. 3), but more 
Botanical Gazette, vol. 71] [446 
