66 DISEASES OF FIELD & GARDEN CROPS. [OH. 



of the doctor's view it may be called to mind that several 

 members of the germs of fungi to which Isaria belongs, 

 grow naturally on living animals. 



It is not usual for fungi to grow on living or, indeed, 

 dead animal material, yet botanists are familiar with 

 several such examples other than the ones already cited. 

 The familiar fungus of the salmon disease, Saprolegnia 

 ferax, Kutz., is one, and the white dusty fungus named 

 Empusa, muscce, Cohn., so common on flies on our window 

 panes in autumn, another. This is said by some observers 

 to be merely a second condition of the Saprolegnia. The 

 ringworm fungus Oidium porriginis, Mont., is another 

 example ; Microcera coccophila, Desm., a parasite of Cocci, 

 insects of the American blight class, is a third ; 

 Onygena equina, Pers., which grows on the hoofs of dead 

 horses, is a fourth, and the list might be greatly extended. 

 Fries has described an Agaricus, named by him A. 

 nauseosus, growing on the carcass of a wolf, and A. 

 ostreatus, Jacq., has been seen in this country by Mr. C. 

 B. Plowright growing on the dead body of a stranded 

 whale ; Onygena apus, B. and Br., is not uncommon on 

 bones. These instances are not mentioned with the view 

 of showing that Isaria fuciformis, B., is capable of killing 

 cattle, but to indicate that other and, in some instances, 

 closely allied fungi can support themselves on living and 

 dead animal substances. 



It is extremely difficult to suggest any means for the 

 destruction of the Isaria^ partly because the fungus falls 

 from the grass to the ground on the slightest touch, and 

 partly because so very little is known of the fungus or its 

 habits. The whole subject requires investigation. Some 

 crops might be saved by removing the greater part of the 

 grass before September, or by the substitution of some 

 crop on which the Isaria could not grow. As humidity 

 probably favours the growth of the pest, good and careful 

 drainage might prevent its spreading. No doubt many 

 insects carry the conidia, or spores, from place to place 



