Notes. 
16 
whose neck had not opened. The tissue upon which the sporangia 
are inserted is thin-walled, and its cells have granular contents; it 
contrasts sharply with the cells of the prothallus which have a large 
vacuole and walls which stain much more deeply with haematoxylin. 
As in the case of Lcistraea dilatata , the stages seen render it 
probable that the sporangia follow the usual course of development. 
Two layers of tapetal cells are formed which surround a considerable 
mass of sporogenous tissue. Many of the sporangia fail to attain full 
development; they remain colourless, and in time wither. A few 
have been found, however, with a well-developed annulus of a dark 
colour; these contained spores which have not, however, been 
examined in detail. 
In one case two ramenta overarching a group of sporangia were 
seen. At first sight it seemed possible that they might correspond 
to an indusium, but, when taken in connexion with another example 
in which a cylindrical process, which bore sporangia laterally, 
terminated in an apogamously produced bud, another explanation 
appears more probable ; this will be referred to again below. 
It is worthy of note that another variety of this species has been 
found to produce young plants, the first fronds of which bore 
numerous prothalli while still in connexion with the stem k The 
prothalli on which these plants appeared had been subjected to 
repeated subdivision, a process which in other species 2 has been 
found to induce apogamous development of the sporophyte. Unfor- 
tunately nothing is known of the manner in which these peculiar 
plants of Scolopendrium were produced, but it is possible that they 
arose apogamously. The case of Scolopendrium would then be 
comparable to that of Trichomanes alatum 3 , in which apogamy and 
apospory co-exist. Prothalli have been found to arise directly from 
the older fronds of another variety of Scolopendrium k 
An attempt will now be made to bring the peculiar modification of 
the life-history cycle of these Ferns into relation with previously 
recorded cases of apogamy, and to estimate its theoretical bearing. 
A full consideration of these points must be deferred until more 
extended observations have been made. 
There seems no reason to doubt the prothallial nature of the 
1 In a paper by Mr. E. J. Lowe, read at the Linnean Society, February 20, 1896. 
2 Stange, loc. cit. 3 Bower, Annals of Botany, Vol. i, p. 300. 
4 Druery, Linn. Soc. Journ., Vol. xxx, p. 281. 
M 2 
