12 
The study of the development of the embryo in the Marat- 
tiaceae is a problem of special difficulty. The embryos are only 
occasionally met with, and a very large number of prothallia 
must be examined before even a small series of embryos can 
be secured. Moreover, the earlier stages are very difficult to 
fix and section satisfactorily, as they are peculiarly lable to 
shrinkage, and it is almost impossible to secure really satis- 
factory sections of the early stages. This has made it impos- 
sible to be perfectly certain of the exact relations of the organs 
of the older embryos to the earlier divisions. 
A marked peculiarity of the young sporophyte first shown 
by Luerssen and Jonkman for Marattia and Angiopteris, and 
confirmed by later observation for these genera as well as for 
others, is the orientation of the primary organs of the young 
sporophyte with reference to the archegonium. The primary or 
basal wall in the embryo is always transverse instead of being 
vertical, as it is in the ordinary ferns, and the first leaf, in- 
stead of being formed from one of the quadrants next the 
archegonium, arises from the half of the embryo which is 
turned away from the archegonium, and so grows straight 
upward emerging upon the upper side of the prothallium instead 
of emerging on the lower surface and curving upward. Moreover 
the embryo retains for a much longer time its oval form, and 
the development of the external organs takes place much later 
than in the other ferns. 7 
It has been generally assumed that as in the leptosporangiate 
ferns the cotyledon and stem are of epibasal origin, the root 
and foot hypobasal. This was the conclusion reached by both 
Jonkman and Farmer, and my earlier studies on Marattia 
douglas led me to the same conclusion. A further study, — , 
however, as well as an examination of the embryos of Angiopteris ie 
and Kaulfussia, have led me to think that this is not the case, 
but that the whole of the hypobasal region contributes to the 
foot, and that the root is developed secondarily from the epi 
basal region as well as the stem apex and the cotyledon. 
While in the Polypodiaceae, the young organs of the embry 
