552 THE BOOK OF GARDENING. 



of the soil, which colouring increases until the pots or pans 

 are completely covered with a growth which, in general 

 appearance, greatly resembles the common Liverwort. It is 

 from this strange growth that the young Ferns ultimately 

 develop, according to the different species, in a space of time 

 varying from two to six months from the time of sowing. It 

 is during a certain state of apparent dormancy, lasting some- 

 times several weeks, that the fecundation takes place, and it is 

 also during that particular time that, to encourage fertilisation, 

 a uniform rate of moisture is most important. 



"Pricking" Off. — The spores having germinated freely, and 

 grown to form a dense mass of Lichen- or Liverwort-like 

 appearance, it is necessary, or even indispensable, that they 

 should be "pricked off." This delicate operation consists in 

 separating this singular growth into small patches, and 

 depositing them in other pots filled with a material or compost 

 similar to the one in which they have been sown ; its object 

 is to give the .young . seedlings the required room to develop 

 themselves, for if allowed to crowd and overgrow each other 

 in- the seed-pan, they are very liable to damp off. After 

 having been pricked off, these seedlings should for a few days 

 be treated as they were previously.. They should be gradually 

 inured to the action of the air by tilting on one . side the 

 glass cover, which may, in a short time, be removed altogether. 

 They may now be watered overhead , and placed where they 

 will receive plenty of light, and ' where they Will require to be 

 kept damp. In some cases this operation may have to be 

 repeated several times before the fronds make . their appearance, 

 or before the young plants are strong enough to be potted 

 singly, and treated as recommended in the section on " Ferns 

 in Pots." 



Garden Hybrids. — The interest attaching to Ferns pro- 

 pagated from spores is greatly increased by the chance thus 

 afforded of finding something new, which result cannot be 

 achieved if the plants are propagated in any other way. The 

 number of garden hybrids, or supposed hybrids, already in 

 existence, and obtained in that' way, is steadily increasing every 

 year, and it may be safely stated that in the majority of cases 

 these productions are not merely freaks of nature, but, as may 

 be seen by the accompanying illustration of Adiantum 

 Birkenheadii (Fig. 344), real acquisitions, possessing great deco- 

 rative qualities, such, for instance, as the beautiful Polypodium 

 May ii, exhibited at the Temple Show in May, 1899, and in 

 which the pleasing frilled character of the edges of the fronds, 

 combined with their lovely bluish colour, makes it one of the 

 prettiest Ferns known. The most distinct and most beautiful 

 of all Polypodiums, P. Schneideri, with its large, very plumose 

 fronds, is another illustration of what may be found among 



