Boiver. — Studies in the Phytogeny of the Filicales. 277 
leaf-like lobes’, seen especially in G. laevigata. These are compared by 
Campbell with those of Fossombronia , or Dendroceros. But the most 
important characters for comparison are provided by the sexual organs. 
Campbell has shown that the neck-canal-cell of the archegonium (except 
in G. polypodioides) commonly divides into two cells. This is regarded as 
a primitive character. As regards the antheridium, Rauwenhoff examined 
various species of Eu-Gleichenia , but of the Mertensia section only G. fla- 
bellata , and found in all that he examined a general correspondence of the 
antheridium with that of the Polypodiaceae. But other species belonging 
to the Mertensia section examined by Campbell are characterized by the 
much larger size of the antheridium, this being especially marked in 
G. laevigata and G. pectinata. 
The number of spermatocytes traversed in a median longitudinal 
section gives a numerical basis for comparison. From Campbell’s pub- 
lished drawings the numbers appear as follows : G. polypodioides (§ Eu- 
Gleichenia) — 19. G. (. Mertensia ) laevigata — 95, 35 ? 76. G. (. Mertensia ) 
linearis — 30, 42. G. (. Mertensia ) pectinata — 46, 23, 60, 62. From this 
it appears that there is considerable variability not only within the genus, 
but also in specimens of the same species. It is a criterion which must 
be used with caution. The chief point is that the numbers are high com- 
pared not only with those of other Ferns, but also with Pteridophyta at 
large. From published figures (mostly taken from Campbell’s ‘ Mosses and 
Ferns ’) it appears that typical numbers of spermatocytes seen in section are 
for Ophioglossum 87, K aidfussia 61, Marattia 31, Osmunda 32, O node a 21, 
N ephr odium (Kny) 16, Woodsia (Schlumberger) 17, 18, 16, 14, 14, 13. In 
other Pteridophytes the numbers are for Equisetum 56, and Lycopodium 46. 
From a comparison of these figures it follows that the antheridia of 
G. laevigata are exceptional in showing in specific cases a larger number of 
spermatocytes in median section than any of the Pteridophytes quoted. 
On the other hand, the figures for the Mertensia section of Gleichenia as 
a whole are in excess of those for the Leptosporangiate Ferns. N ephr odium 
with about 16, and Woodsia with an average almost the same, may be taken 
as typical for the Leptosporangiate types. And so it is seen that the Mer- 
tensia section of Gleichenia , together with the two outstanding species 
G. linearis and G. pectinata , occupy a position altogether exceptional among 
Ferns, while the latter species are extremes even among Pteridophytes at 
large, in respect of the number of their spermatocytes. This, going along 
with the large output of spores in the Mertensia section, and other relatively 
primitive characters, indicates in an unmistakable way that it is among the 
most primitive types of the living Filicales. 
But the characters upon which this general conclusion is based do not 
always run parallel. Thus G. flabellata , which in its anatomy, its sorus, 
and its spore-output appears as the most primitive species, has not the 
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