274 FLY FUNGUS. PAET n. 



It is the mycelium or spawn which does the mischief, 

 by supplying the fungus with food at the expense of 

 the victim. The spores of the Botrytis Bassiana find 

 a nidus in the breathing pores which open into the 

 trachea of the silkworm ; they develop their mycelium 

 in the air-tubes, which are soon filled up ; it then extends 

 into the fatty matter under the skin, which nourishes 

 the worm during its dormant state, and, as soon as that 

 matter is exhausted, the victim dies. 



In autumn, the common fly, though quite dead, may 

 be seen adhering to many parts of a room, especially 

 to the window glass, as if it were alive. In this state 

 it is always surrounded by a halo about an inch in 

 diameter of whitish dust, consisting of the spores of the 

 Empusa Muscse, or fly fungus. The body of the fly is 

 much distended, the rings of its abdomen are sepa- 

 rated by the growth of the mycelium from within, and 

 all the contents of the body having been consumed 

 by the parasite, nothing remains but a hollow shell 

 with a thin felt-like layer of the interlaced mycelia 

 of innumerable fungi, for the fly fungus increases with 

 wonderful rapidity within the insect. Mr. Berkeley 

 believes the fly fungus to be merely a condition or 

 phase of one of those anomalous moulds which grow 

 on dead fish, making them conspicuous as they float 

 on the surface of the water, by the foggy halo which 

 surrounds them. Different kinds of parasitic fungi 

 may exist at the same time. Dr. Leidy found a variety 

 in the stomach of the Passalus cornutus, a beetle that 

 lives upon decayed wood. Fungi do not attack the car- 

 nivorous beetles. 



Man is not exempt from these parasites. Fourteen 

 different species of fungi were discovered by Mr. Hogg 

 in ' as many cutaneous diseases. There cannot be the 

 smallest doubt of cutaneous disease being induced by 

 inoculation with fungi ; merely rubbing certain species 



