22 MUSHROOM GROWING AND SPAWN MAKING. 



From the standpoint of obtaining pure cnltnres, the tissue-culture 

 method is capable of very general application. Three considerations 

 render it particularly important, as follows: (1) WTien a suitable 

 culture medium is at hand, a pure culture may be obtained almost 

 invariably from a young, healthy plant. (2) Cultures may be made 

 from fungi the spores of which have never been brought to germina- 

 tion. (3) Pure cultures are made by direct inoculation; that is, 

 dilution cultures are rendered wholly superfluous. In the case of 

 Agaricus campestris and other Basidiomycetes, in which the gill- 

 bearing surface is protected until the spores are produced, it is pos- 

 sible, with the precautions previously mentioned, to obtain the spores 

 pure, or practically pure, and at the same time in considerable quan- 

 tity. This is not possible with the great majority of fleshy fungi, 

 which are truly gymnocarpous. Again, members of the genus Cop- 

 rinus are deliquescent, and here it is impracticable to secure spores 

 by the spore-print method. In the Lycoperdacese and other Gaster- 

 omycetes it has been found that bacteria are frequently present in the 

 tissues by the time the spores are formed, and, even if the spores 

 could be germinated, direct cultures would perhaps be seldom possi- 

 ble. By the tissue method it is only necessary that the plant shall be 

 so young that the cells of the tissue are capable of growth and that 

 there are no foreign organisms present in the tissue. In this connec- 

 tion it may be stated that in the Phallinea?, Hymenogastrinea?, and 

 Lycoperdinea3 no representative has been germinated, while in the 

 Plectobasidinese germination is known only in the case of Spliaero- 

 holus stellatus and PisolHhus crassipes. 



"VMien the natural conditions of germination shall have been more 

 definitely ascertained, direct spore-culture methods should in prac- 

 tice, perhaps, replace the pure tissue-culture methods in making 

 virgin spawn. This would render unnecessary a tedious portion of 

 the work, and the process of spawn making would be thereby made 

 less expensive. 



A discussion of the respective practical merits of the spore and tissue 

 methods would not be complete Avithout reference to the comparative 

 vigor, or productive power, of the resulting mycelium. In the growth 

 of the mycelium no difference could be detected. The writer has also 

 grown mushrooms from spawn produced by both of these methods; 

 but the results do not indicate that there is any advantage for the one 

 over the other. It is believed, therefore, that the processes of basidial 

 and spore formation are in this regard relatively unessential, or at 

 least do not intensify whatever invigoration may, in general, result 

 from mere sporophore production. It is to be expected, perhaps, that 

 any and all colls of the sporoj^hore may be invigorated by whatever 

 is to be gained by the assemblage, or concentration, in the ditferen- 



