OP MICROSCOPIC OBJECTS. 85 



the leaves are the reservoirs for the spores, which in many 

 instances somewhat resemble green velvet, and are arranged 

 in stripes, round masses, and other forms. The spores are 

 usually covered with a thin skin, which is curiously marked 

 in some specimens, often very like pollen-grains. The man- 

 ner in which these spores with all their accompaniments 

 are arranged, their changes and developments, afford almost 

 endless subjects for study; different ferns presenting us with 

 many variations in this respect totally invisible without the 

 aid of the microscope. The hymenophyllnms (of which two 

 only belong to England) are particularly interesting, and 

 the structure of the leaves when dried makes them beautiful 

 objects, often requiring no balsam to aid their transparency. 

 Portions of the fronds of ferns should be mounted as opaque 

 objects, after having been dried between blotting-paper, 

 when they are not injured by pressure; but care must be 

 taken to gather them at the right time, as they do not show 

 their beauty before they are ripe, and if over-ripe the ar- 

 rangement of the spores, &c., is altered. The spores may 

 be mounted as separate objects in the same manner as 

 pollen, before mentioned, and are exquisitely beautiful when 

 viewed with a tolerably high power. The number of foreign 

 ferns now cultivated in this country has greatly widened 

 the field for research in this direction ; and it may also be 

 mentioned that the under-sides of many are found to be 

 covered with scales of very beautiful forms. A small 

 piece of the frond of one of these may be mounted in its 

 natural state, but the removal of the scales for es anima- 

 tion by polarized light will be described in another place. 

 The mosses also are quite a little world, requiring but a low 

 power to show their beauties. The leaves are of various 

 forms, some of which resemble beautiful net-work ; the 

 " urns " or reservoirs for the spores, however, are perhaps 

 the most interesting parts of these objects, as also of the 

 liverworts which are closely allied to the mosses. These 

 urns are generally covered by lids, which fail off when 

 the fruit is ripe. At this period they are well fitted for th> 



