i 1 9 
Danaea simplicifolia , Rudge . 
available showed no definite single apical cell, and Prof. 
Campbell found the same to be the case with Marattia 
Donglasii 1 . A plantlet was investigated in which, besides 
the cotyledon and a quite young second leaf, there was the 
earliest rudiment of a third; but this rudiment seemed already 
to have a two-celled apex, one of the cells being in the last 
stage of karyokinesis, although the new anticlinal wall had 
not been formed. Hence it is exceedingly probable that 
in the case of the cotyledon and the subsequent leaves, 
if at any time there is a single apical cell it can only be of 
exceedingly transitory duration. 
The root presented the same difficulty ; the only pro- 
mising young embryo, Fig. 1 6 , did not show any cell, or 
cells, which could be recognized as constituting the growing- 
point of the future root. The root of Fig. 8 might have 
shown the condition at a later stage, but it unfortunately got 
broken off before imbedding and was sectioned by hand. It 
does not show anything decisive. Attempts were made to 
study the primary roots of young plants, but these were 
nearly all either actually injured, or in such bad condition at 
the tip as to make otherwise successful microtome-sections 
useless. In one case, however, a longitudinal section (one of 
a microtome-series) was obtained which showed a remarkably 
large cell which, judging from its position and the condition 
of the adjacent tissues, seemed to be the apical cell, although 
it was not quite axially median. Sections of the adventitious 
roots left no doubt that, in their case at least, the growing- 
point consisted of a few equivalent initials, in one case a well- 
marked group of four. 
Summary. 
The genus Danaea , as exemplified by Danaea simplicifolia , 
Rudge, is found to agree very closely with Angiopteris and 
Marattia , both in the gametophyte and in the embryo- 
sporophyte. Perhaps the most important point of difference is 
the presence of septate, or multicellular, rhizoids in the former 
1 Loc. cit. , p. ii. 
