242 



Mycological Bulletin Nos. 61 and 62 



[Vol. IV 



air where they ficat about until they come into contact with other flies. 

 When a spore ccmes in contact with a healthy fly a fungns thread is pro- 

 dviced which soon makes its way to the inside and continues to branch and 

 grow till it kills the fly when it comes to the surface and forms a new crop 

 of spores. 



One of the most interesting group of parasitic fungi are the beetle 

 fungi. They are extremely =mall and can only be seen by a strong lens. 

 They are fourd on the legs of the water beetles and usually found on a 

 certain joint of one leg. This localization is accounted for on the ground 

 that plant sexes are often formed on different plants so sexual cells of 

 fungi may be brourht in ccr tact by the breeding acts of the ir.sects. 



I-"ig. 190. Cor'-dy-ceps HER-cii'i.i;-A. CiiANT Caterpillar I'ungus. 

 Ijlanation. M. E. Ilanl, Cliillicothe, Ohio. 



See text for ex- 



Thc c;iteri)illar fungus is the most coinmnn and i)rescnts many interest- 

 ing featuris because of its ability to produce a variety of spores, each 

 special i^ed for a definite purpose. Spores may l)e produced upon fruiting 

 bodies similar to figure ]9(). As soon as a spore falls upon a calerjiillar it 

 germinates, sending out germ-threads in the body cavity. Here these inrm- 

 threads form new spores which move freely in the fluid of the cater])illar. 

 These sjjores germinate imtil the entire body cavity and nniscle ilber are 

 thoroughly permeated by mycelium threads.' These threads continue to 

 branch and grow until they have absorI)ed all the larva's soft parts, retaining 

 not only the external form of the caterpillar but also the internal form of 



