76 Journal of Agricultural Research Voi. xii. No. » 



Sporophores were produced when various kinds of inocula were used, 

 such as wood, tissue, spores, or the myceUum from other cultures and on 

 a great variety of artificial culture media. The wide range of genera 

 and species covered by this investigation, together with the large number 

 of sporophores produced, clearly proves that the sporophore production 

 here reported is not an accident, but is a constant and permanent per- 

 formance determined in the great majority of cases by the presence of 

 light and to a very limited extent by the character of the substratum. 

 Aeration and humidity are two other factors which also enter into sporo- 

 phores production on artificial media. 



INFLUENCE OP SUBSTRATUM ON CHARACTER OF HYMENIUM 



The influence of the host or substratum on the character of the spore- 

 bearing surface is well illustrated in the several strains of Polysticius 

 hirsutus when grown in artificial cultures. In all of these strains the best 

 developed and well-defined pore surfaces are produced on carrot, malt, 

 and parsnip agars. On these the pore surface is fairly typical of that 

 produced in nature, both as to size and color of pores. In the prune agar 

 the pore surface is usually reduced in the majority of the tubes to a few 

 scattering irpiciform spines. On some of the prune-agar tubes the spines 

 are not flattened like those of an Irpex, but are round like those of a 

 Hydnum. In the corn-meal tubes the hymenium in a large majority of 

 cases is very similar to that produced in various species of the Thele- 

 phoraceae, being reduced to a smooth or slightly granular surface in which 

 there are no definite pores. In all of the tubes (carrot, malt, prune, corn- 

 meal, and parsnip agars) there is an enormous production of spores irre- 

 spective of the character of the hymenium. In fact, in some of the tubes 

 the first evidence of any sporophore production is the deposit of spores on 

 the opposite side of the culture tube when even a careful examination 

 with a hand lens fails to show any signs of pores or spines. 



The size, shape, and coloring of the pores and tubes produced in artifi- 

 cial cultures on many of the agars are practically identical with those 

 found in nature for a given species. However, it often happens that in 

 abortive sporophores on certain agars the coloring is not as pronounced 

 as on agars where the sporophores reach their full development. In 

 Polyporus cinnabarimis, for instance, the sporophores produced on 

 potato agar are nearly white, while the same strain will produce the 

 typical grenadine- red to flame-scarlet pores on malt. 



TRUE PILEI IN ARTIFICIAI, CUI.TURES 



One of the most interesting facts brought out in this investigation was 

 that in all of the thousands of cultures made with the hundreds of sporo- 

 phores produced not a single one had a typical pileus, unless the fungus 

 was a gill-bearing form ( Agaricaceae) , when the culture tubes were so 

 placed that the slant faced the light in such a manner that its rays were 



