36 BRITISH FERNS 



The archegonia, or seed-vessels, are as a rule situated just with 

 the indentation of the heart-shaped prothallus, and the antherid 

 or equivalents of pollen masses among the root-hairs covering tl 

 larger and other half of the prothallus. The prothallus is most rete 

 tive of life, and will bear with impunity almost any amount 

 cutting up. We will therefore suppose two pans of thinly sown spore 

 each one of a different variety or species ; as soon as the protha 

 are half grown, i.e. before any fertilization is likely, we take a ke< 

 razor and cut each prothallus across just below the indentatio 

 We do this in both pans, carefully removing the male halves in eac 

 and neatly embedding them in the soil, just touching the arch 

 gonial portions of the other variety or species which have been le 

 in situ, and which if deprived of root-hairs by the operation w 

 certainly develop more if gently pressed into the soil and kept clos 

 In this way the chances of self-fertilization would be reduced to 

 minimum, and those of a cross increased to a maximum, as tl 

 subsequent growth of both halves would bring them into extreme 

 close juxtaposition. There is, however, a good deal of irregularil 

 in the arrangements of the organs on the prothallus, and hence th 

 sort of division cannot be depended upon absolutely as separatir 

 the sexes. 



To Mr. E. J. Lowe, as we have said, must certainly be accorded tl 

 merits of the first most striking hybrid, viz. that effected by hi. 

 between a cruciate form of Polystichum angular e and a dense form 

 P. aculcatum, the result being a cruciate aculealum, and we may he: 

 remark that it is only where absolutely distinct forms such as the 

 are crossed that we can be sure that the progeny is a cross at a 

 because once a Fern or other plant has broken away from tl 

 normal plan of growth, its progeny is apt to vary again, probab 

 more or less on the same lines, but not necessarily so. Fortunatel 

 however, numerous crosses have been effected under circumstanc 

 of choice which eliminate this doubt. Mr. Clapham, for instanc 

 sowed the finely cut form of Polypodium vulgare, known as el 

 gantissimum, with another form known as P v. bifido-cristatum, i 

 attenuate crested form. Elegantissimum has a peculiar knack 

 partial reversion to the normal. The offspring of the cross was n< 

 merely a more or less tasselled form of elegantissimum, which migl 

 have been a secondary sport per se, but when it tried to get back 

 normality it produced a frond of the true type of bifido-cristatm 



Mr. Schneider, in his marvellous hybrid between this same elega- 

 tissimum and the huge exotic Phlebodium aureumfinds the hybridis 

 confirmed by precisely the same character of partial reversion. ! 

 another cross between Athyrium filix fcemina Victories, the mo 

 remarkable Fern yet found, bearing percruciate and tasselled frond 

 and A.f. f. setigerum with translucent, bristly excrescences all ov 

 it, the result is A.f. f. Victories, true to type, but bristling througho' 

 with the setigerum character. Crosses and hybrids of this cla 



