CULTIVATION. 399 



convenient size ; they should be half filled with good 

 drainage material, with the smallest particles at top, 

 when another fourth of depth should be occupied by 

 fine soil, half sand and peat, one quarter loam, with a 

 sprinkling of finely-broken sandstone or soft brick 

 slightly pressed down on the top ; it should then be 

 watered and time allowed for the whole to become 

 uniformly moist ; then the spores to be very thinly dis- 

 tributed over it, the whole covered with a bell-glass 

 or a piece of glass same size as pot, to be placed on 

 its rim, allowing a space of about one inch between it 

 and the surface of the soil. In order to keep the whole 

 moderately and constantly moist, the pots should be 

 placed in pans of water of half an inch depth, care being 

 taken not to allow the soil to become over saturated; 

 and whenever any copious condensation takes place 

 on the glass, it should be carefully sponged off. As 

 the spores germinate, and the Prothallia become 

 crowded, so as to touch each other, they should be im- 

 mediately thinned, and if it is desirable to save the 

 thinnings they can be removed in little clumps on the 

 particles of brick or sandstone to other pots prepared 

 as for spores. It is not, however, with all our care in 

 sowing different species in separate pots, that the 

 species sown come up in the pot in which it was sown: 

 plants of it may be found in other pots, or in different 

 parts of the house on moist surfaces. This is easily ac- 

 counted for, as the least motion of the air carries away 

 the spores while in the action of sowing, and indeed 

 all superfluity of spores may be with profit distributed 

 over the whole house, the moist walls often affording 

 abundance of young plants. It also often happens that 

 a good crop of Pteris aguilina is the result, its spores 



