Jan, 14, 1918 Cultures of Wood-Rotting Fungi on Artificial Media 79 



Table XVI shows that there were 56 strains of wood-rotting fungi 

 which produced sporophores on malt agar, 52 on corn meal, 48 on prune, 

 44 on carrot, 27 on parsnip, 14 on potato, 11 on celery, 11 on beet, 10 on 

 bean, and only i on alfalfa agar, while there are four of these agars pre- 

 eminently suitable for sporophore production — viz, malt, com meal, 

 prune, and carrot, in the order given. 



POSITION OF SPOROPHORES ON MEDIA 



One most interesting fact in reference to sporophore production on 

 artificial media is the fact that a very large percentage, probably more 

 than 95 per cent, of the sporophores were developed on the upper half of 

 the slant. No perfect sporophores have ever been observed by the writers 

 other than on the slant, although the agar in the tubes often dries out 

 sufficiently to leave ample room for the sporophores to develop from the 

 slant to the bottom of the tube over a distance of from 60 to 80 mm. 

 Whether this means that the formation of the sporophore was dependent 

 upon a small amount of moisture or whether it needed the greater aeration 

 which the upper end of the tube afforded is not known. In many in- 

 stances, especially with the Stereums, the fruiting surface was formed in 

 a narrow zone at the extreme upper limit of the agar slant. The studies 

 so far made indicate that an important factor in this case is probably 

 the drier condition of the agar at the upper end of the slant. It would 

 seem that if the drying of the agar was the only requisite for the forma- 

 tion of sporophores that as the agar dries in the lower portion of the 

 tube a condition would be reached which would normally produce sporo- 

 phores; yet such is not the case. The by-products produced by the 

 fungus may be more or less deleterious to the formation of sporophores; 

 and, since such by-products would be more abundant in the lower portion 

 of the tube than under the slant, it follows that few, if any, sporophores 

 would develop there. 



DENSITY OP MYCELIUM AND SPOROPHORE PRODUCTION 



Another very peculiar fact develops that the sporophore production 

 usually occurs on that portion of the agar slant where the aerial growth 

 of mycehum is the least. If a dense mass of mycelium forms over the 

 entire agar slant, the chance for the formation of pores on such a surface 

 is materially lessened. This may explain to some extent why sunlight 

 plays an important part in the production of sporophores, since cultures 

 kept in the dark usually develop a denser mass of mycelium on the surface 

 of the slant than corresponding cultures in the light. There are many 

 species of fungi which have been tried in both light and darkness in 

 which the aerial growth is very limited, even when grown in the dark; 

 and still no sporophores were produced when in darkness, but were pro- 

 duced in the light. 



