676 MICROSCOPIC STRUCTURE OF HIGHER CRYPTOGAMS 



wall of the sporange is composed of flattened cells, applied to each 

 other by their edges ; but there is generally one row of these thicker 

 and larger than the rest which springs from the pedicel, and is 

 continued over the summit of the sporange, so as to form a projecting 

 ring, which is known as the annulus (fig. 519). This ring has an 

 elasticity superior to that of all the rest of the wall of the capsule, 

 causing it to split across when mature, so that the contained spores 

 may escape ; and in many instances the two halves of the sporange are 

 carried widely apart from each other, the fissure extending to such a 

 depth as to separate them completely. In Osmunda (the so-called 

 ' flowering fern ' or 'royal fern ') and Ophioglossum (adder's tongue) 

 the sporaiiges have no annulus, or one greatly modified. It will 

 frequently happen that specimens of fern-fructification gathered for 

 the microscope will be found to have all the sporanges burst and 

 the spores dispersed, whilst in others less advanced the sporanges 

 may all be closed ; others, however, may often be met with in which 

 some of the sporanges are closed and others are open ; and if these 

 l>e watched with sufficient attention the rupture of some of the 



FIG. 518. Sorus and indusium of 



Aspidituu. 



FIG. 519. Sorus and cup-shaped 

 indusium of Deparia }iroUjf,'a. 



sporanges and the dispersion of the spores may be observed to take 

 place while the specimen is under observation in the field of the 

 microscope. In sori whose sporanges have all burst, the aniiuli 

 connecting their two halves are the most conspicuous objects, look- 

 ing, when a strong light is thrown upon them, like strongly banded 

 worms of a bright brown hue. This is particularly the case in 

 Scolopendrium, whose elongated sori are remarkably beautiful 

 objects for the microscope in all their stages; until quite mature, 

 however . they need to be brought into view by turning back the 

 I wo indusial folds that cover them. The commonest ferns, indeed, 

 which are, found in almost every hedge, furnish objects of no less 

 beauty than those yielded by the rarest exotics; and it is in every 

 respect a niosi valuable training to the young to teach them how 

 much may be found to interest, when looked for with intelligent 

 eves, even in the most familiar, and therefore disregarded, specimens 

 of Nat nrc's handiwork. 



The 'spores' (fig. "rJO. A) set tree by the bursting of the spo- 

 s, usually have a somewhat angular form, and are invested by a 



