34 Journal of Agricultural Research voi. xii. no. 2 



fruiting bodies or sporophores of wood-rotting fungi can be produced from 

 pure cultures on artificial media. In this paper the writers have only 

 given in a general way the results of somewhat extended investigations 

 on many species of wood-rotting fungi, leaving for a later article a large 

 amount of detail and the discussion of special methods and culture media 

 which they have found very valuable in working wdth this group of 

 organisms. 



GENERAL METHODS OF EXPERIMENTATION 



ORIGIN OF CULTURES 



The initial cultures of all of the wood-rotting fungi under investigation 

 by the writers have been obtained from the three following sources: 

 (i) Small pieces of diseased wood, (2) small pieces of sporophores, and 

 (3) spores. Pieces of inoculum 4 or 5 mm. in diameter have been found 

 to be better than smaller pieces. The old idea that the smaller the piece 

 the freer it is from contamination is good reasoning theoretically, but in 

 actual practice pieces of the size mentioned above have been found more 

 viable than small bits and as free from contamination. The larger the 

 piece the greater are the chances of viable mycelium being present. The 

 pieces should be inserted endwise into the middle of the agar slant until 

 about one-half of the wood is buried in the agar. Care should be taken 

 to avoid, as far as possible, burying the wood in the agar, since the cover- 

 ing of agar excludes the air and either retards or prevents entirely the 

 fungus from starting on the culture medium. A pair of long-handled 

 scissors or forceps are especial!}' suitable for this work. 



In initial cultures the writers have found it very convenient to use a 

 series of 10 tubes, including 2 tubes each of carrot, malt, commeal, 

 prune, and parsnip agars. These agars have been found to give a fairly 

 good growth of mycelium, and at the same time indications of the fruiting, 

 cultural characters, etc. of the organism may be obtained even from 

 these initial cultures. 



The writers have made approximately 10,000 cultures of wood-rotting 

 fungi in their preliminary studies here reported. All of the inoculations, 

 both initial and subcultures, have been made in an open room without 

 the use of any special inoculating chamber. The percentage of pure 

 subcultures obtained when the original tube was uncontaminated has 

 been very high. For instance, out of 1,000 transfers recently made only 

 7 contaminated tubes were found. 



METHODS USED IN MAKING SUBCULTURES 



The writers desire to describe here a method which they have found 

 very useful in making transfers of fungus cultures when 10 or more 

 transfers are to be made from the same tube. The instruments used in 

 these transfers are a pair of long-handled scissors made by lengthening 

 the handles of a pair of dissecting scissors, a small square glass jar with a 



