I 9 2 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 

 these species is Merulius lacrymans, which 

 Fir;."i 4 6. 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 

 germinate, 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 



