io Campbell. — Observations on the Development 
conjugating nuclei were seen, the clearness with which 
the nuclei were differentiated from the colourless cytoplasm 
indicates that this would prove a very satisfactory plant for 
studying fertilization. 
The Embryo. 
I was not fortunate enough to get satisfactory preparations 
of the earliest stages of the embryo. A number of single- 
celled embryos were seen, but the following stages were not 
found. This much can be said, however : — after fertilization, 
the egg enlarges to several times its original size before 
dividing, and the first wall is parallel to the surface of the 
prothallium, as in Angiopteris , and as is also the case in Isoetes 
and Bquisetum. This is followed by the median and octant 
walls, but in what order it is impossible to say. 
The youngest embryo found is shown in Figs. 22 and 23. In 
this the basal and median walls were very plain, and several 
divisions had appeared in the octants. Compared with other 
ferns there is less regularity in the arrangement of the early 
division-walls in the octants, and this is undoubtedly asso- 
ciated with the much less definite growth in the different 
members of the young plant. Still, the regular formation of 
octants, and the lateral segments cut off from these before 
any periclinal walls are formed, probably indicates that at 
first, as in the mature organs of most ferns, the growth is 
from a single tetrahedral cell. In the next older embryos found 
(Figs. 24 and 25) the primary divisions had already ceased 
to be certainly distinguishable, and the limits of the octants 
could no longer be positively determined. As in other ferns, 
the first or basal wall determines the position of the primary 
organs, the cotyledon and stem-apex arising from the epi- 
basal cell, the root and foot from the hypobasal. The 
Marattiaceae differ, however, from all the known forms in the 
position of these organs with reference to the archegonium. 
Whereas in all other forms yet investigated the cotyledon is 
derived from one of the quadrants adjacent to the neck of the 
archegonium, in Marattia (and Farmer has shown this to be 
