397 
The general course of events is much the same in all these cases. The primary 
cause of the injury is want of oxygen at the roots. 
Of all the subaerial agents which damage pines, however, none are perhaps more 
to he feared than the acid gases of our larger manufacturing towns. Sulphurous 
acid, hydrochloric acid, chlorine, coal gas, and such like chemicals are fatal to pines, 
even in very small quantities, and it is no doubt to these rather than to the increased 
percentage of carbon dioxide, soot, or to the diminished light, that the foggy 
exhalations of large towns owe their enormous power for evil. Nor can we wonder 
at this when we reflect that many pines are mountain species, growing normally in 
those purest of atmospheres, which attract us for the very reasou of their purity. 
Considerable space is devoted to Nectarina cucurbitula , to the larch 
canker ( Peziza ), and to the latest views concerning Uredineons para¬ 
sites. The European larch is said to be an alpine plant, and most of its 
diseases affecting it when under cultivation are primarily attributable 
to the unsuitable environment of lowland regions, especially to the 
earlier springs. 
In this country the diseases of the larch are almost all initiated by late frosts, 
damp soil, insufficient sunlight, and alternations of periods of drought with periods 
of excessive moisture, in varying degrees of combination. Late frosts, or chills 
which approach such, are among the most deadly agents. The tender tufts of bright 
green foliage, to which the larches owe their spring beauty, are usually forced out 
in the country a month or six weeks too soon. Once they get well over this early 
dilatory period of sprouting, all is safe; their safety is insured in their mountain 
heights (1) by their not beginning to awake from the long winter rest till danger of 
frosts is practically over, and (2) by the extreme rapidity with which they run 
through the period of tenderness. 
The germinal liyplue of Peziza willlconiii will not penetrate the sound 
cortex of the larch, but a slight frost injury or other wounds enables 
them to do so. 
Trametes radieiperda u attacks the living roots of Finns sylvestris , 
P. strobus , and others, sending its snow-white mycelium beneath the 
cortex, and traveling thence up the stem to finally penetrate the wood 
by way of the cambium and medullary rays. The ro tting of the wood 
rapidly follows, with symptoms so peculiar that the presence of this 
fungus can be concluded with certainty from them.” The author says 
that T. radieiperda is u now known very thoroughly from the recent 
magnificent researches of Brefeld,”* but cites Hartig to the effect that 
u moats, dug so as to cut off sound trees from infected ones, have been 
of service.” 
Agaricus melleus, though a less pronounced parasite, is not less destructive; the 
details of its action on the timber are different and its mode of spreading from root 
to root in the soil, by means of its long purple-black, cord-like mycelial strands, 
called Rhizomorpha, also differs. But the net results are much the same in both 
cases. Very tangible signs of the presence of Agaricus melleus, in the absence of the 
tawnv yellow toadstools, are afforded by the copious outflow of resin from the dis¬ 
eased roots and base of the stem of the affected trees, and by the above rliizomorphs 
in the rotting wood and soil around. 
Most of the Polgpori mentioned are decidedly wound fungi, that is to say, they 
* Brefeld’s own conclusions in this connection are as follows: “ Open isolation moats 
do not offer the least hindrance to the spread of this fungus, but, on the contrary 
greatly favor it, by breaking the diseased roots and inducing the formation of an 
unusual number of spore-bearing organs (seeUntersuchuugen, Heft Viu, pp. 182-184)* 
