218 Commercial Gardening 



with warm water, or immersion of the pan in such until the water per- 

 colating from below just floods the prothalli, may bring about the desired 

 alliances usually effected by means of a dewdrop, as above explained. 



Where hybridization is desired to be effected, the two sorts of spores 

 should be sown together on somewhat thicker lines, since cross fertilization 

 can only take place naturally if the prothalli are crowded together. It is, 

 however, beyond doubt that a flooding from below, as mentioned above, 

 when the prothalli are about mature, ma^' have the effect of transporting 

 the fertilizing antherozoids from one prothallus to another and thus effect- 

 ing a cross. Spores, however, as we have suggested above, do not all ger- 

 minate with the same rapidity, and hence a sowing of a slow -growing 

 species must be made at one time, and that of its more rapidly developing 

 companion later on, to permit of simultaneous maturity. Some crosses are 

 said to have been effected by severing prothalli of two kinds and bringing 

 the two different halves in close contact, an idea which is quite feasible, as 

 the prothallus is very tenacious of life, and will bear such an operation 

 with impunity. 



One point must be remembered in crossing or hybridizing, and that is, 

 that it is practically impossible to determine what is a cross or a hybrid 

 except by the clear appearance of the two parental characters in the off- 

 spring. The pollen equivalent cannot, like pollen itself, be collected and 

 applied in the right quarter as with flowers; the material is too minute to 

 handle and the chance of self-fertilization cannot be eliminated, besides all 

 which, in sowing varietal forms, and it is only by sowing two very distinct 

 types that any recognizable result is possible, there is always a great 

 possibility of a purely independent " sport " occurring amongst the seedlings 

 of either form, which may not owe its origin to cross influence at all. 



We may now conclude by a few remarks on propagation by other means 

 than spores. The usual methods of layering bulbils of proliferous fronds, 

 or stolons of stoloniferous ones, are too well known to require description. 

 Plants with creeping rhizomes, like the Polypodies, Davallias, &c., only 

 require portions of such rhizomes or fleshy rootstocks to be severed with 

 a frond or two and a growing point to be treated as rooted plants, and 

 plants producing offsets laterally only require these to be prised off and 

 planted for them to establish themselves at once. 



There are, however, potentialities in some Ferns which are entirely 

 latent, and can only be rendered effective artificially. The Hartstongue, of 

 which there are so many beautiful forms, some of which, the Cri spurns or 

 frilled ones, are perfectly barren, is a case in point. This Fern in time 

 forms a long caudex built up for some inches of persistent bases of the old 

 dead fronds. Lifting such a plant and commencing at the bottom, these 

 bases of a dark colour and sausage-shaped and from J-l in. long, can be 

 forced off the central core by downward pressure one after another to the 

 number of, it may be, several scores. When the top is nearly reached, the 

 crown may be replanted and will speedily re-establish itself. Each of these 

 bases will be found to be provided with a bundle of roots; these should be 



