Notes . 
133 
in thickness, and is very easily recognised ; but from the mode of its 
formation it can hardly arise otherwise than by the conversion of a 
layer, already present in the protoplasm, directly into cellulose, and 
it appears to be the presence of this substance, arranged in a definite 
plate-like manner, which determines the splitting referred to. The 
first membrane cuts the spore into an apical and a basal portion, and 
while the latter for some time undergoes no further change, the apical 
cell is divided almost simultaneously into a number of cells whose 
arrangement can still be followed even in quite old protballia. When 
the first primary cells are formed, the nuclei are again distinguishable 
by haematoxylin, but they are of exceedingly small dimensions ; and 
with this change the staining properties of the protoplasm become less 
marked. Divisions in all planes proceed very rapidly in the upper 
portion of the prothallium, and the rudiments of the archegonia are 
laid down much as in the Marattiaceae. Periclinal division of single 
superficial cells into two takes place, the upper of which gives rise 
to the neck, and by repeated division forms four stories, each story 
being divided into four cells arranged like quadrants of a cylinder. 
The lower cell gives rise to the central series, in which a neck canal- 
cell is cut off, and then a ventral canal-cell, from the oosphere. It 
can now be seen that the canal-cells thrust themselves between the 
neck-cells, and produce a distortion in the two lower stories so 
great that in some cases these are not easily recognisable in later 
stages. 
While these changes have been taking place in the upper of the two 
primary cells, the basal one is dividing, but comparatively slowly, and 
it is easily distinguishable in that the cells which arise from it remain 
of a large size as compared with those formed in the upper part of the 
prothallium. 
In spite of repeated search through a great number of preparations, 
it has not been found hitherto possible to arrive at a definite conclu- 
sion as to the mode of cell-division which prevails in the secondary 
stage, for no karyokinetic figures could be detected ; nevertheless it is 
highly probable that the process does not differ in any important 
respect from that prevailing in other plants, and the arrangement of 
the nuclei about the walls of recently formed cells makes this 
supposition almost a certainty. 
I have purposely omitted any reference to the researches of other 
observers in the present note, and it was not my object to attempt 
