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Proceedings of the Royal Society of Edinburgh. [Sess. 
same sporangium and spore are also shown in fig. 11. The latter was 
large, and measured approximately 10 // in diameter. Iron was entirely 
absent from its membrane, and this was also the case with the membranes 
Figs. 8-11, — Phycomycites Frodinghamii (Ellis). 
Figs. 8-10. — Stages in development of sporangium. A swelling was formed at the end of a hypha, 
which increased in size till the mature form, seen in fig. 10, was attained. xl466. 
Fig. 11. — Sporangium, the membrane of which has burst. 
a. Spore attached to sporangium and liberated by the bursting of the wall of the latter. 
Spore is approximately 10 ix in diameter. 
h. Sporangium with wall broken in. 
c. Neighbouring hypha. 
This sporangium is shown photographed in Plate I, fig. 4. xlOOO. 
of the other spores which were observed. Inside the same sporangium the 
outlines of another spore were observed, but it was too vague to be shown 
in the photomicrograph. This spore had the same dimensions as the other 
Figs. 12 and \Z.— Phycomycites Prodingliarnii (Ellis). 
Fig. 12— Two sporangia apparently crushed together whilst partially superimposed. In the space 
between the walls of these two sporangia a group of four spores, a, is shown, x 1266. 
Fig. 13.— Two swellings on short stalks arising from adjacent hyphse. x800. 
just mentioned. I concluded that the sporangium must normally have con- 
tained four spores. After a prolonged search, which, owing to the masking 
effect of the iron deposition, could be successful only in the event of meeting 
a crushed sporangium, I succeeded in observing a broken sporangium inside 
which four of these large spores in the tetrad position were seen. The 
