TJie Phascums, or Earth Mosses. 1 73 



comes in at once with the three-inch and the Milcroskop als 

 Ocular. 



Many persons have Huyghenian telescope eye-pieces higher 

 than those supplied with microscopes, and they will do very 

 well for experiments. If not too high they will succeed; and 

 if they are too high, they will serve to show when another opti- 

 cal combination must be resorted to in order to afford enough 

 light and a sufficient field. 



Although the preceding remarks relate chiefly to the 

 employment of so low an objective as a three-inch, the principle 

 upon which they are founded indicates when a two-thirds may 

 be made to do better than one-fourth, or one-fourth than one- 

 eighth. 



THE PHASCUMS, OR EAETH MOSSES. 



BY M. G. CAMPBELL. 



Have any of our readers observed on moist shady banks or 

 fallows, or recently-turned earth, a kind of greenish hue, hardly 

 more to the naked eye than a verdant mildew? When next 

 seen, let them possess themselves of a small bit, by sliding the 

 point of a penknife under a little tuft of it. The plant is far 

 too delicate for the touch of human fingers. 



We will suppose this done, and that the tuft is placed under 

 the microscope at the true focal distance from the object-glass. 

 What a forest is revealed by that magic instrument ! True, 

 the trees are, many of them, all but stemless, and their modest 

 fruit hides amid the foliage ; but how exquisite is that foliage, 

 especially if taken fresh from a damp spot, or if suffered to 

 imbibe a drop of water, which, filling the cells, will expand the 

 leaf to its full proportions. 



These plants are of rapid growth and brief duration. 

 Several of them may be found in autumn, and also in spring ; 

 some in winter. Wilson has enumerated and described eighteen 

 distinct species of earth-moss, exclusive of the Archidium, or 

 clay-moss, which is an allied species. They are chiefly annuals, 

 with a capsule, very shortly pedicellate, and a calyptra falling 

 away entire, while the capsule is without a deciduous lid, and 

 when mature bursts irregularly to give exit to the small spores, 

 the provision for a future generation of Phascums. These 

 spores the earth receives and garners till congenial circum- 

 stances wake up the germ of vitality that slumbers within them, 

 when they shoot forth their littlo thread-like thalli by hundreds, 

 attain the dignity of perfect plants and of parents, and then 



