T8 THE PARASITIC FUNGI OF INSECTS. 



hence the name Afetarhhiiim Leptophyei. The insects were found 

 attached to the lower surface of the leaves, parallel to the median 

 vein, and with the head turned towards the petiole. The ventral 

 surface of the insect was covered with hyphae, causing its adherence 

 to the leaf The mycelium is pluricellular, and the spores are of 

 two kinds — very small, ovoid conidia, and larger elongated ones, 

 divided by a transverse septum. 



Another species has a peculiar life-history. It attacks a Calli- 

 phora, and it appears that only one form of its spores are 

 developed in this host, germinating in the digestive tube of the 

 fly. The CaUiphora is a favourite food of frogs and lizards, and 

 it is only after it has been de\-oured that the second more perfect 

 spore is developed in the excrement of the animal that has 

 devoured it. 



There is a great deal to be learned yet about this interesting 

 group of fungi, which has so long been serving a great and hitherto 

 hardly recognised service to Nature's economy by ridding it of a 

 superabundance of one form of animal life, which, if not checked 

 by this and other means, would soon destroy vegetable life from 

 the surface of the globe. 



CORDYCEPS. 



This insect fungus still retains its place among the Ascomy- 

 cetes, although the knowledge of its life-history has become much 

 more full since first it was placed in this group, when it was known 

 under the name of Torrubia. Several species of Isaria — formerly 

 supposed to belong to a totally distinct genus — are now found to 

 be merely a phase in the hfe-history of Cordyceps ; consequently, 

 we have here an interesting example of dimorphism. 



The perfect form of Cordyceps affecting insects consists of a 

 club-shaped body, of a colour varying from red or orange to 

 brown, containing numerous sacs or ascospores, filled with 

 numerous filiform spores, which break up on their ejection into 

 numerous round secondary spores. These, on coming in contact 

 with any moisture, swell and put out germ-tubes which penetrate 

 the skin of a suitable host, if they come in contact with it and 

 ramify in the superficial tissues of its body. After a time, 

 numerous long spores, called cylinder conidia, are produced on 

 the tubes of the mycelium, which, becoming detached, pass into 



