2l6 



subsequently sowed P. v. cristatum with other exotic 

 members of the same genus, and undoubtedly obtained 

 •crested forms of the latter among the results of his 

 sowing ; cresting however per se occurs so frequently as a 

 sport that these results, though we see no reason to doubt 

 their hybrid origin, are not so conclusive, though neverthe 

 less encouraging for further efforts. 



The British species of Ferns curiously enough have 

 not only afforded a far greater number of "sports," 

 crested, plumose and otherwise varied, than the exotics, 

 but there are many types of variation among them at once 

 beautiful and curious which have not appeared at all 

 among the latter, and which, if they could be introduced 

 by judicious crossing, would certainly give rise to very 

 attractive and valuable decorative plants, besides, and 

 this is a material point, adding in all probability to their 

 hardiness and consequent ease of cultivation. In Ferns 

 fortunately the would-be hybridiser is not handicapped as 

 in flowering plants by incompatibility between the size of 

 the pollen grains and the length of stigma to be traversed to 

 reach the embryo seed. Undoubtedly in most plants these 

 factors are nicely co-adapted ; a very long-styled stigma, 

 like that of a Lily, is associated with large pollen grains, 

 and very short-styled flowers with smaller ones. Practi- 

 cally, however, all Ferns, from the smallest to the largest, 

 perform their reproductive functions on the same micro- 

 scopic scale, the prothallus or tiny primary leaf produced 

 from the spore is much of a size throughout all the genera, 

 and as the antherozoids are free-swimming organisms, a 

 little difference in dimensions forms no obstacle to their 

 reaching the archegonial bud. 



Hence no obvious structural difficulty stands in the way 

 of mating the tiniest Fern with the largest Tree-Fern ; all 

 that is necessary is some degree of kinship. This fact 

 clearly widens the field of operations considerably, and, 



