FUNGI IN GENERAL 97 



The most recent definition of Fungi with which we are 

 acquainted is that given by Saccardo in 1889: " Cryptogamic 

 plants, cellular, destitute of chlorophyll, for the most part 

 having a mycelium, either parasitic or saprogenous, for the 

 most part aerial." That is to say, they are " cellular crypto- 

 gamic plants, chiefly developed in the air, either epiphytal or 

 saprophytal, and mostly with a mycelium, but destitute of 

 chlorophyll." Kecognising the difticulty in constructing a 

 definition which shall approach to mathematical precision, we 

 may accept the above as the nearest approach to accuracy 

 which ingenuity has yet devised. Considerable emphasis has 

 generally been placed on the presence of a mycelium in the 

 larger majority of Fungi, as the analogue of the protonema of 

 mosses and the thallus of Lichens. The analogy, however, is 

 imperfect, and rather superficial in most cases, since a true 

 mycelium is almost a thing by itself. 



The gill-bearing Agarics, such as the common mushroom, 

 have a conspicuous filamentous mycelium, from which the 

 stem arises, and which permeates the matrix to such an extent 

 that, in a compact form under the name of " bricks," it con- 

 stitutes the medium through which cultivation is maintained. 

 This mycelium or spawn, although only produced artificially in 

 the case of a single species, is universal to a greater or less 

 extent in the Hymenomycetal Fungi. In a certain sense it is 

 the representative of the root in flowering plants, but may 

 be better regarded as the vegetative system of the Fungus. 

 During the winter, in terrestrial species, this mycelium remains 

 in the soil in a hibernating condition, so that a crop of the 

 resultant Fungi may be looked for in the succeeding year. It 

 is an open question what portion of the Fungus crop in 

 any given year should be referred to a perennial mycelium, 

 and what portion to the germination of the spores of the 

 previous year's crop. Some mycologists contend that in the 

 majority of instances, as in the commoner species, the continuity 

 is maintained by means of the mycelium. We have observed 

 ill the case of Agaricus {Flammula) carhonarms, which occurred 

 plentifully on charred ground not under cultivation, that, the 

 ground not being disturbed, the same Agaric made its appear- 

 ance regularly for four or five years, and then rapidly declined 



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