240 Boodle. — On the Production of Dzvarf Male 
For examples of intrasporangial germination in other Ferns we may 
quote the case of the Hymenophyllaceae, in which the spores sometimes 
undergo the first few divisions in the closed sporangia (Sadebeck, ’ 79 , p. 159). 
It is also interesting to recall a case described by Scott (’ 04 , p. 18) of ger- 
minating spores in a fossil Fern-sporangium, especially as the specimen 
appears to be allied to the Osmundaceae. Here, however, the wall of the 
sporangium is broken, and it is uncertain whether dehiscence may have 
taken place before the germination of the spores. It may be a similar 
occurrence to that described in Todea hymenophylloides (Boodle, ’ 00 , 
p. 484), viz. the germination of spores in a ruptured sporangium, when 
dehiscence has been weak, so as only to eject a few of the spores, and 
probably this is also the explanation of the case figured by Atkinson (’ 94 , 
p. 7, Fig. 12) in Pteris serrulata. In a second case described by Scott 
(’ 06 , p. 170, Fig. 27) in a fossil Fern, the germination may well have taken 
place in the closed sporangium. 
Borodin ('68, p. 438) states that he obtained a certain number of dwarf 
male prothalli by sowing spores of Allosurus sagittatns in water in the 
light, and transferring them into darkness after 5-6 days (i. e. just when 
germination was beginning). The culture afterwards showed that most of 
the spores had remained unchanged, but that a certain number had pro- 
duced dwarf gametophytes. The prothallus was reduced to a single cell, 
and bore from one to three antheridia. It is just possible that these reduced 
prothalli, and some of those described by Schacht and others, may have 
really been produced by previous germination in the sporangia from which 
the spores were taken for sowing. 
The fact that in filmy species of Todea a certain degree of dampness 
can, by preventing dehiscence of the sporangium 1 , cause extreme reduction 
of the gametophyte, comparable to that shown by Salvinia and Azolla (in 
the male prothallus), is of considerable interest, as showing how easily such 
reduction may be brought about in relation to external conditions. It will 
be important to learn whether Todea barbara , Moore, which is not a filmy 
species, would behave in the same way, and what result would be obtained 
by placing the sporangia of other Ferns under various conditions. It is 
possible that a study of this subject may yield information bearing on 
reduction of the gametophyte in other phyla besides the Filicineae. 
Summary. 
When plants of Todea Fraseri are kept in a sufficiently damp 
atmosphere, the sporangia do not dehisce, and a number of spores germinate 
in the closed sporangia. In drier air the 'sporangia dehisce normally. 
1 It would be interesting to know whether dehiscence of the sporangium is ever prevented by 
dampness in the natural habitats of these species. 
