1 1 6 Ford . — The Anatomy of 
the case in regard to the gametophyte. Many of the 
differences seen in. the structure of the mature plant are due 
of course to its manner of life ; thus, for example, the re- 
duction of the stem and of the elements composing the 
vascular tissue throughout the plant, the very small amount 
of sclerenchyma found, and the presence of the large air- 
passages are all correlated with its aquatic life. The sporangia 
are larger than in most Ferns ; they are scattered singly on 
the leaves and are not aggregated into sori. In regard to the 
development of the spores, their germination, the formation ^ 
and subsequent growth of the prothallus, no important 
differences are seen between Ceratopteris and the Poly- 
podiaceae as a whole. According to Kny 1 and Van Tieghem 2 , 
in regard to the formation of the antheridia, Ceratopteris 
resembles Aneimia and P ter is, though, when mature, the 
antheridium projects somewhat less from the surface of the 
prothallus. In regard to the archegonia, Campbell 3 ’ states 
that they are developed independently of the original growing 
apex, the archegonial meristem being lateral. In the embryo 
Kny 4 has pointed out that both the two anterior quadrants 
form the first leaf, and from this the stem, arises laterally at 
a later stage. Kny has laid some stress on this point in his 
discussion as to the origin of Dicotyledons and Monocotyle- 
dons. These groups have, in his opinion, originated inde- 
pendently of each other from the Vascular Cryptogams ; 
he brings forward this point in regard to the formation of 
the young stem as a resemblance between Monocotyledons 
and the Filicineae, both of which are furnished with but 
one cotyledonary leaf. Campbell 5 , on the other hand, is 
of opinion that the line of descent of the Angiosperms as 
a single group passes through the Eusporangiate Ferns and 
possibly through the Isoetaceae. Ceratopteris , which he 
describes as an 4 aberrant genus,’ may form the connecting 
link between the Polypodiaceae and Marsilia. He compares 
1 Kny, 1875, p. 15. 3 Van Tieghem, 1891, p. 1382. 
3 Campbell, 1895, p. 375. 4 Kny, 1875, p. 58. 
5 Campbell, 1895, p. 518. 
