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IX, C, 8 Campbell: Macroglossum Copeland 921 
glossum is a conspicuous mucilage duct (m), which is wanting 
in the leaf of Angiopteris. A striking feature in Macroglossum 
is the development of a conspicuous ridge separating the elon- 
gated sori, so that the latter are sunk in a sort of trough, very 
much as is the case in Danaea. This is especially marked in 
M. Alidae, where only the upper portion of the sporangium is 
free. In Angiopteris (fig. 1, C), the sporangia are entirely 
exposed. 
In Macroglossum there is a conspicuous indusium composed 
of branching hairs, which form a fringe on either side or the 
sorus. In M. Alidae these hairs reach nearly or quite to the 
summit of the sporangia, and are very much like those found 
in Archangiopteris.2. These indusial hairs are much less devel- 
oped in Angiopteris. : 
. 
Fic. 2. Surface cells of the sporangium seen from the side; the tannin cells are shaded. 
A, Macroglossum Alidae; B, M. Smithii; C, Angiopteris. 
The elongated sorus of Macroglossum presents a quite different 
appearance from that of. Angiopteris. On account of the sub- 
mersion of the sorus between the ridges referred to, the sporangia 
project only slightly above the level of the leaf-surface, and 
they are so closely crowded as to be scarcely distinguishable, 
even with a lens, so that the sorus closely resembles superficially 
the elongated solid synangium of Danaea. The individual spo- 
rangia are smaller, but much more numerous than in Angiopteris 
where there are usually from 6 to 15 sporangia in each sorus. 
In Macroglossum Alidae there may be more than 60 sporangia 
in the sorus. 
Seen in median section (fig. 2, C) the sporangium of Angiop- 
teris is nearly circular in outline, being strongly convex both 
dorsally and ventrally. In Macroglossum (fig. 2, B) a simi- 
lar section is nearly pear-shaped, the sporangium being much 
less convex dorsally than in Angiopteris, and having the ventral 
surface almost flat. 
*Christ & Giesenhagen, Pteridographische Notizen, Flora 86 (1899). 
126079-—8 
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