ORIENTATION OF THE PLANT EGG 313 
is] 
mestigated the embryos of Pteris, Aspidium, Adiantum, and 
fymnogramme, giving in his f/. 3 the figures of Pteris embry- 
gay which have become classic. The first wall in the Pteris 
abryo runs almost parallel with the archegonial axis, trans- 
mse to the prothallium, and divides il aes 
te egg into a smaller anterior epibasal 
mia larger posterior hypobasal hemis- 
tere. The normal position of the arche- 
®eis ventral, so that at first the root 
mi foot octants are directed obliquely 
spward, If, however, the archegone is 
*normally produced upon the upper side 
* (sometimes normally) upon the mar- 
® of the prothallium the orientation is 
wtessentially modified with reference to 
“atchegone. This is the reverse of the condition observed 
* Marchantia, but, as in the liverwort, there is no revolving 
the egg in its archegone venter. Fig. § shows the normal 
“sition of the egg, the epibasal hemisphere being directed 
. = the morphological apex of the prothallium and obliquely 
| Ward the substratum. 
Fic. 8. Embryo of 
Pteris. 
*niryegeny of Marsilia.—The Hydropteridee have received 
their share of investigation during the 
last fifty years. Hofmeister’ in 1851 
B examined the embryo of Pilularia, and 
later Hanstein’* made a very complete 
study of the Marsilia embryogeny, offer- 
ing in p/. rr of the work cited numerous 
B satisfactory figures of the early see 
ae As in other leptosporangiate and, indeed, 
*.9-—Embryo of as in all heterosporous ferns, the basal 
Marsilia, wall is parallel with the axis of the arche- 
gone. Here, however, unlike Isoetes, the 
F 
ee 
— Unters, 106. 1851, oe 
M4: 197, ne und Entwickelung der Gattung Marsilia. Jahrb. wis>- 
