364 FERNS I BRITISH AND FOREIGN. 



ence in the fertility of the spores of these two divi- 

 sions is very remarkable; this is, it must be remembered, 

 as found with the plants under cultivation, and as with 

 many true Ferns we find, from experience, the spores 

 of the latter seldom germinate in less than eighteen 

 months after having been sown. On the contrary, in 

 the Desmobrya group, many require but two or three 

 weeks, and occasionally certain species of Gymno- 

 gramma and Cheilanthes will germinate in as many 

 days. From the irregularity, however, in this respect 

 it is in a great measure governed by the state of, and 

 conditions which surround, the seed ; from repeated 

 trials with spores of Brainea insignis, Prothallia were 

 produced in forty- eight hours. Consequent on this 

 irregularity, it is impossible to state what time of the 

 year is most suitable for sowing to ensure success, 

 especially for imported spores, which should be sown 

 as soon as received, provided a proper condition can 

 be given them. Therefore extra attention must be 

 paid when it unfortunately occurs that the young 

 Ferns are in their Prothallium stage during the winter 

 season, to keep them from damping and the growth of 

 conferva and musci. When it is desirable to increase any 

 particular species by spores, some precaution is neces- 

 sary to secure them in a proper ripe condition, and 

 without spores of other species growing near being 

 mixed with them. The fructified frond should be taken 

 as soon as the spore-cases on the plant begin to open, 

 and placed between sheets of paper in a moderately 

 dry place for a few days, at the end of which time there 

 will be escaped spores in abundance. - These should 

 be immediately sown in pots prepared in the following 

 manner ; four to six-inch pots are generally the most 



