Ferns 2I5 



The life-history of a Fern may thus be summarized. Fern, spore, pro- 

 thallus, antheridia, archegonia, incipient seed, Fern again. This, however, 

 is the normal course; but Nature in her infinite variety has contrived to 

 bring about the same results i.e. Fern from Fern by numerous short cuts. 

 Thus in the familiar Ferns, Asplenium proliferum and Nepkrdepis exaltata, 

 we see the shortest cuts of all, since the parent Fern bears in the first case 

 a veritable multitude of youngsters on its fronds, youngsters so precocious 

 that they often bear another generation of their own before being detached; 

 and, in the second case, by a multitude of stoloniferous runners on Straw- 

 berry lines, by which it can be propagated ad libitum. These represent 

 the types of numerous Ferns of bulbiferous or stoloniferous habit in which 

 a new generation is produced by direct outgrowth of the parent, and to 

 this class belong those Ferns which produce lateral offsets. These proli- 

 ferous forms, however, relate to the adult Fern, and do not affect the pro- 

 thallic life-cycle already described, and which has also been varied in every 

 conceivable way. Some years subsequent to Suminski's elucidation of the 

 normal cycle, Professor Farlow, in the United States, demonstrated that 

 with some Ferns (amongst them our Lastrea pseudo-mas cristata) a non- 

 sexual bud was generated on the prothallus and produced the parental 

 type, the antheridia and archegonia and incipient seed being thus elimi- 

 nated, an ordinary bud being produced instead. The writer then dis- 

 covered on a form of Lady Fern (Athyrium filix-fcemina, var. clarissima, 

 Jones) that certain excrescences yearly produced on its frond backs, and 

 which had persistently refused to yield plants by means of the sporeheaps 

 which they were assumed to consist of, were really capable, when layered, 

 of developing prothalli direct without the intervention of the spore, these 

 prothalli proving to be perfect by the production of numerous characteristic 

 plants. This implied the elimination of the spore and spore cases, which 

 Professor Bower eventually found were partially aborted at an early 

 stage, the prothalli eventually growing from the remaining cells. This 

 was termed " apospory ", or spore elision. Mr. G. B. Wollaston imme- 

 diately followed with an example of a Polystichum (P. angulare, var. 

 pulcherrimum), in which the extreme tips of the subdivisions of the 

 fronds grew out into prothalli which produced plants, though of imperfect 

 character. This cuts out the sporeheap altogether, and lias been termed 

 "apical apospory" and the first found form "soral apospory" to differentiate 

 them. Since then this phenomenon has been found in several other species, 

 mostly of British Ferns and in varietal forms. Dr. Lang's experiments 

 with spores of abnormal varieties went even the length of demonstrating 

 that a Fern might possibly be perpetuated indefinitely without getting 

 beyond the " prothallium " stage, since he found spores produced on the 

 prothallus itself; and if these had produced offspring (which they failed 

 to do), and inherited the retrogressive character, this would have con- 

 stituted a reversion to a very low type of vegetation indeed, resembling 

 the Marchantias or Liverworts. 



To the Fern-cultivator a good grip of the particulars we have given of 



