ЕЕВМ CROSSING AND HYBRIDIZING 37 
bear their certificates of origin upon their fronds: in each сазе 
the parents are pure-bred original finds, and in their offspring the 
strong parental marks are distinctly brought out. At Kew there 
are a great number of marked instances among the Polystichums 
raised by Colonel Jones and others by crossing his polydactylous 
find of P. angulare with many other varieties. In this Fern there 
must have been some special prepotency, for the crosses were in- 
numerable, but in every one that we have seen as yet they are ear- 
marked by the parental defect of producing here and there non- 
polydactylous divisions and irregular furcation to boot. One and 
all present this feature, which establishes the dual origin convin- 
cingly, but spoils the plants. 
Among hybrids between species, we must not omit to mention 
Mr. Lowe's indubitable cross between Scolopendriwm vulgare and 
Ceterach officinarum. On examination of the fronds it is seen 
that they are of Ceterach pinnation, though confluent at the 
tip and quite scaleless, while the fructification can be detected оп 
the basal pinnæ as in faced pairs, i.e. Scolopendrium fashion, and 
further up, as single lines, i.e. in the character of the Spleenworts. 
We do not know whether this plant is still alive, but the fronds 
per se establish its hybrid character and determine both parents 
with certainty. Fortunately, whether alive or dead, fronds are in 
the writer’s possession as confirmation of its occurrence and of the 
description here given. In European Ferns, page 137, a presumed 
natural hybrid between the same two species is figured, but con- 
sidering Ше great varietal capacity of Scol. vulgare, and the existence 
of numerous pinnatifid forms, the hybridism in that case is, to our 
mind, very doubtful, especially as it is fully fertile. 
Having thus cited a few of the conclusive evidences of the possi- 
bility of crossing, not merely varieties, but also widely different 
species, and given a few hints as to the modus operandi, the next 
thing is to give some idea of the directions in which this possibility 
may be utilized to the best advantage. Polypodium Schneideri 
is, we think, eloquent with two possibilities of extreme value. 
The one is that of enhancing the simple beauty of many exotics 
by alliances with the highly ornate forms which our British hardy 
species have assumed, both under purely natural conditions. as 
wild finds and under selective culture of the progeny which they 
have yielded. The other is the increased capacity of exotics, so 
hybridized, to withstand low temperature, due to the infusion of 
hardy blood. Та Ferns, thanks to the curious fact that the pro- 
thallus, or green scale upon which the flower homologues are pro- 
duced, is almost constant in size throughout all species except 
the Filmies, the minutest species and the largest Tree Fern com- 
mence their career under practically identical conditions, and cross- 
ing and hybridization therefore are not limited as in flowers by 
incompatibilities between length of stigma and size of pollen. 



























