192 ABOUT FUNGI. [CHAP. 
which has found its way here from South America. 
Timber trees, too, suffer terribly from fungi, among 
the most destructive being several species which are 
known under the general term of “dry rot;” the 
state of wood so attacked is well known, though it 
is perhaps not quite so well known how it 
is caused. One of the most destructive of 
Se these species is Merulius lacrymans, which 
Fic. 146. penetrates the cells of the wood, and robs 
them of their lignine and cellulose, thus 
rendering their tissue friable. ; 
The effects of fungi upon animals is no less remark- 
able. Many insects are attacked by fungi during 
life. Botrytis Bassiana is a great impediment to the 
production of silk owing to its destruction of the silk- 
worm. It is known under the popular name of Mus- 
cardine. The spores are probably eaten by the 
silk-worm, as they seem to commence growth in the 
insect’s large intestine; though if the spores be 
simply rubbed upon the silkworm’s skin, they will 
scerminate, and their threads prey upon the fatty 
tissue till the whole of the insect’s body be filled with 
them. Most of our readers must have noticed how 
in autumn the flies stick to the window-panes after 
death, though their extended limbs and fresh appear- 
ance might lead one to suppose they were still alive. 
On closer examination we shall find that the fly is 
standing upon a mat of delicate silk threads spread 
upon the glass. These threads are really the myce- 
lium of a fungus which attacks the fly. The fly 
becomes sluggish, and rests upon some surface, pre-— 
ferably on the window-pane, and passively awaits the 
