FERTILISATION AND PROPAGATION. 



Besides the kinds above enumerated, there are some other Ferns, British 

 and exotic, partaking to a certain extent of the barren, or of the accidentally 

 fertile, characters ; but the instances given above have been thought 

 sufficiently numerous to show that these characters arc shared principally, 

 if not even exclusively, by plumose forms in both sections, and that repro- 

 duction from spores, however advisable in many respects as a general operation, 

 becomes, in such peculiar cases, absolutely impossible. 



Lately we have had to record two other modes of propagation, each of 

 them very little known to the public in general, but which may be classed 

 among the most important discoveries of recent date bearing on the repro- 

 duction of Ferns, and through both of which the young Fern is produced 

 independently of the phenomena described in the part of this chapter devoted 

 to propagation from spores. One has been called Apogamy (from apo, afar, 

 and gamos, marriage), and the other Apospory (from apo, afar, and spora, a 

 spore or seed). In the former process, Apogamy, which was first observed 

 by Professor Farlow in connection with the well-known Pteris cretica, but 

 which is now known to affect several other Ferns, notably Nephrodiwm 

 (Lastrea) Filix-mas cristata, the young Fern is produced as a bud from 

 certain parts of the prothallus, without the formation of sexual organs. The 

 sexual process, as the name indicates, is in this case completely abolished, 

 the production of spores being suppressed. 



In the other departure, Apospory, which has been brought prominently 

 before the public by Mr. Charles T. Druery — who, in a series of most interest- 

 ing lectures upon the subject before the Linnean Society, stated that in certain 

 Ferns the prothalli are produced as outgrowths from the pinnules of the Fern 

 fronds, and not from the spores — the sexual reproduction is not affected, and 

 the leafy Ferns are developed from the prothalli in the usual way. But the 

 prothallus, according to the variety in .which Apospory was observed, is either 

 modified sporangia or simply a structure of prothalloid nature, without any 

 connection with sori or sporangia. Thus it is that Professor Bower, who 

 made careful and very elaborate investigations of these new modes of repro- 

 duction, states that in Asplenium (Athyrium) Filix-foemina Clarissima — the 

 first plant on which this singular character was observed — the prothalli are 

 modified sporangia; whereas in Aspidium (Polystichum) aculeatum angulare 

 pulcherrimum, in which the same character was first discovered by Mr. G. B. 



