THE AMERICAN BOTANIST. 



3 



but while there may be a common underl^ang law, it is 

 certainly variously played upon. There would appear to 

 be an individual tendency in each sort of tree. 



This matter has been closely studied by the late Thos. 

 Meehan, of Germantown, who with his usual independ- 

 ence, took issue with certain accepted statements. It is a 

 matter too deep for discussion here. Mr. Meehan's 

 pamphlet, which is well worth perusal, is Bulletin No. 29 

 of the Department of Agriculture of Pennsylvania, and is 

 illustrated by figures. 



The bark of a tree is a complete microcosm, where 

 many creatures live, move, and have their being. Every 

 one has observed how upon a wet day, the north or north- 

 east sides of trees, more especially, are clothed with vivid 

 green. If we scrape off some of this granular or slimy 

 matter and examine it under a compound microscope, we 

 will find it to consist of a complex mass of several kinds 

 of low vegetation. Indeed, upon bark may be seen algae, 

 fungi, liverworts, mosses and lichens. While some of these 

 are found on any tree, others are confined to certain sorts. 

 Such is especially the case, we have found, with mosses. 

 These are very coquettish as to habitat. 



The vegetable covering, of varying colors, from in- 

 tense green to yellow or orange, add very much to the 

 beauty and attractiveness of a tree. Lichens, indeed, 

 sometimes form long, hoary beards upon the trees, till 

 they resemble, "Harpers hoar with beards asleep on their 

 bosoms." One often finds a tree, like the beech, scored 

 with circular patterns, intricate and pretty. Great 

 spreading fungi, forming elaborate brackets, will be seen 

 on some forest trees, occasionally tier above tier. These 

 are indicative of disease, but are the effect rather than the 

 cause. If fungi appear on a tree, it is pretty safe to con- 

 sider it doomed as the delicate threads of mycelium are 

 then wide spread beneath the bark, permeating the vital 

 tissues. If the trees are ones own, they should be guarded 

 against wound or abrasion. City trees are in parlous 

 state. Indeed, there should be formed a Society for Pre- 



