PROCURING OBJECTS. 77 



which divide the cells are sometimes found to take a spiral 

 course. To observe this structure, soak the moss in water, to 

 expand the cells. 



It is essential, in collecting mosses, to preserve the theca or 

 seed-vessel, for without it the genera cannot be determined; 

 while this part, with the calyptra and operculum, are the most 

 valuable for the microscope. 



Algae. Are interesting objects. The green, mucous, slime- 

 like matter in damp garden walks, and the hair-like weeds in 

 ditches, are examples of fresh-water algae. The sea-weeds of 

 our coast are marine algae, and are often found having zoo- 

 phytes adhering to them; they are then splendid opaque ob- 

 jects. For mounting in balsam, the smaller kinds, of a bright 

 scarlet color, are the most valuable. 



ferns. The genera are mainly distinguished by the posi- 

 tion and arrangement of the organs of reproduction. These 

 are mostly on the under side, or along the margin of the leaf 

 or frond. They are best examined as opaque objects. They 

 should be collected before they are quite ripe. The spores 

 (seeds) are usually enclosed in brown capsules, each having 

 an elastic ring about its equator, which when ripe bursts, and 

 the spores are dispersed to a distance. Spores may be mounted 

 either as transparent or opaque objects. The development of 

 ferns may be observed by placing the spores in moistened 

 flannel and keeping it at a warm temperature. At first a single 

 cellule is produced, then a second, and so on. After this the 

 first cellule divides into two, and then the others, by which a 

 lateral increase takes place. 



Lichens and Fungi afford interesting objects. The various 

 kinds of mildew upon vegetable substances are familiar ex- 

 amples of minute fungi. 



Organic Fabrics possess much interest in a commercial 

 point of view, in addition to the curiosity arising from the 



7* 



