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A TEXTBOOK OF THEORETICAL BOTANY 



several fruiting bodies can be produced from one mycelium each year and 

 that many mycelia are perennial, some idea will be gained of the scale of spore 

 production. Nevertheless in a given area the population of any species is 

 fairly constant, so that one realises the gross wastage of spores which must 

 occur, and from a bionomic standpoint the reproductive mechanism in the 

 higher Fungi appears to be very inefficient. 



Before closing our account of the Agaricaceae we must refer to luminosity. 

 Since classical times it has been known that decaying wood is sometimes 

 luminous, for Aristotle and Pliny refer to it. It has been shown that the 

 mycelium of many Fungi is capable of producing light, sometimes in sufficient 

 quantity to be visible for 20 yds. This luminosity can only appear in the 

 presence of oxygen and is probably due to chemical changes of a doubtful 

 nature. It appears to have no biological significance. One of the more 

 striking examples is seen in the rhizomorphs of the Honey Fungus, Armillaria 

 mellea, which is a very important wood-destroying Fungus in this country. 

 These rhizomorphs form an almost complete mat of tissue in the region of 

 the phloem of the host plant, and if the bark is stripped off the light emitted 

 by the hyphae is sometimes clearly visible at night. 



Gasteromycetes 



The Gasteromycetes are Fungi in which the hy menial surface is enclosed 

 in a peridium. The interior of the peridium is composed of a chambered 

 tissue called the gleba, on the surfaces of which the hymenium develops. 

 In this way spores when mature are shed into the chambers, and as more 

 and more spores are developed the whole interior of the peridium becomes 

 filled with spores, while the gleba gradually disorganizes and dries up after 

 the formation of the spores. 



Fig. 322. — Lycoperdon pyriforme. Cluster of fruiting bodies 

 at the base of a tree stump. 



