98 PLANT-LIFE 



becomes covered with a sort of olive-green mucus, which 

 contains the tiny spores, and also provides the " smell." 

 This odour is most objectionable; it can be detected a 

 dozen yards away. But, while it is so disagreeable to 

 the olfactory sense of man, it seems to be particularly 

 attractive to " bluebottle " flies. These insects detect 

 the odour, and make straight for its source. They feed 

 greedily upon the mucus, and, of course, swallow the 

 spores which it contains. The spores pass through the 

 alimentary canal of a fly, quite unharmed by the diges- 

 tive process, and thus are dispersed over a consider- 

 able area. Thus, the " Stinkhorn " has adopted 

 quite a cunning " dodge " in order to secure spore- 

 dispersal. 



Fungi of the genus Cordyceps are parasitic on insects 

 and have a life-history worthy of special remark. The 

 spores usually infect insects in their larval stage; they 

 may find admittance to the body along with food, or 

 through the spiracles, or breathing-pores, which are 

 arranged along the sides of the body. The spores 

 germinate and give rise to a mass of filaments, which 

 worm their way through the body and feed on its sub- 

 stances. The larva may survive the infection and 

 pass into a chrysalis, or it may be killed before that 

 change takes place. The dead chrysalis or larva 

 undergoes no change in form, but is converted into a 

 tough, cork-like substance. After a time, the fungus 

 projects a somewhat club-shaped fructification as a 

 means of spore-production and dispersal. This spore- 

 bearing organ, in British species, may be from J to 

 1J inches long. New Zealand furnishes the largest 

 species, some of which produce fruits 6 or more inches 



