meristems of Ferns as a Phylogenetic Study. 371 
advisable to lay much stress upon details of conformation, the 
general progress of the oophyte in our series is shown to be 
from the filamentous type to that of a solid mass of tissue, 
that is, from the simpler type of construction to the more 
complex ; and in this a parallel is seen to the observations 
above detailed on the meristems of the sporophyte in the same 
series. Again, if the antheridia and archegonia be compared 
in this same series, it will be seen that there is a progression 
in their mode of insertion. In the Hymenophyllaceae the 
antheridia are seated on stalks, which appear lateral or ter- 
minal on the filamentous oophyte 1 , and the length of the stalk 
is often as great as the whole depth of the antheridium. In 
the other leptosporangiate Ferns the stalk, if present, is 
usually short, or the antheridium may even be sunk in the 
margin of the thallus 2 ; in the Osmundaceae there is but 
little difference from these, but in the Marattiaceae and 
Ophioglossaceae the antheridium is deeply sunk in the tissue 
of the massive prothallus 3 . In the case of the archegonia 
also it is to be noted that in the Hymenophyllaceae the arche- 
gonia are exposed in groups on the relatively small arche- 
goniophores and have projecting necks 4 , while in the Marat- 
tiaceae 5 they are immersed in the tissue of the thallus and 
their necks project only slightly. Thus in the simpler terms 
of our series the sexual organs are exposed and project, while 
in the most complex forms they are protected by being sunk 
in the tissue of the oophyte. 
Accordingly, whether the general character of the sporo- 
phyte or of the oophyte be considered, the divisions of the 
Filicineae would range themselves serially, according to their 
characters, in the same sequence as that indicated as the result 
of comparative study of their meristems ; and since that is so, 
I think that no further answer is necessary to those who might 
at first feel an objection to the use of such apparently special 
1 Compare Annals of Botany, I, Plate XIV, Fig. 9 ; Plate XVI, Figs. 45-50. 
2 Kny, Monatsber. d. K. Acad, der Wiss. Berlin, 1869. 
3 Jonkman, 1. c. Plate VII, Figs. 87-90. 
4 Annals of Botany, I, Plate XIV, Figs. 10, 16. 
5 Jonkman, 1. c. Figs. 100-105. 
