1921] HAUPT—REBOULIA 447 
commonly the uppermost cell divides again transversely before the 
appearance of the vertical wall in the basal cell, so that the young 
embryo consists of 4 superimposed cells (fig. 4). The latter condi- 
tion has also been noted by WoopBurRN. 
The formation of 3 transverse walls in the early embryo of 
Reboulia represents a behavior quite different from that of the 
other Marchantiaceae which have been studied. The appearance 
© nt et ee Pred sath 
Fics. 1-8.—Stages in development of embryo; 475. 
of 2 vertical walls which intersect each other, after the first trans- 
verse division of the fertilized egg, has been shown by KIENtITz- 
GERLOFF (6) and DurRAND (3) to bea constant feature of Marchantia. 
CAMPBELL (1) has demonstrated the regular formation of an octant 
in the early embryo of Fimbriaria californica, while CAVERS (2) has 
claimed that a similar condition prevails in Reboulia, Krenttz- 
Gertorr has also stated that the embryos of Preissia and 
Grimaldia develop like those of Marchantia, but his figures show no 
~ early stages, and are accordingly unconvincing. Following the 
