THE UTILIZATION OF CERTAIN PENTOSES 
379 
conditions for three weeks they contained practically the same per- 
centage of both alcohol-soluble and alcohol-insoluble pentosans as 
control portions of the same apples in which the cells had not been 
killed. 
When the fungus was allowed to act upon the apple four weeks or 
more the percentages of furfurol-yielding material in the alcohol ex- 
tract and in the solid residue were both higher in the sound half. It is 
evident then that the fungus is able to break down the pentose- 
containing compounds, whether they be pentosans or compounds of 
the pentoses with other sugars, and to use the pentoses. There is no 
evidence at hand, however, to show which pentoses can be used or 
what compounds of the pentoses are most readily broken down by 
the fungus. This was made the subject of further experimentation. 
An attempt was made to determine the value of xylose, arabinose, 
xylan and arabin as compared with glucose as sources of carbon for 
this fungus. 
The fungus was grown on a solution of nutrient salts to which the 
sugars and compounds of the pentoses were added. The medium 
was prepared according to a formula used by Hasselbring^^ in his 
work on Penicillium. It was composed of NH4NO3 i g., KH2PO4 
0.5 g., MgS04 0.25 g., and 100 cc. H2O. To this was added the 
carbohydrate usually in sufficient quantity to make a i percent 
concentration. Three hundred cc. Erlenmeyer flasks were used for 
the cultures. In each of these 100 cc. of the culture solution was 
placed. These solutions were inoculated with the fungus by trans- 
ferring conidiospores from the stock cultures with a sterile needle. 
After a suitable period the felt of mycelium was removed from each 
flask separately, washed with a little water, placed in a tared, glass- 
stoppered weighing bottle and covered with alcohol. The alcohol 
was driven off at low temperature, about 60° C, and the weighing 
bottles with mycelium dried to constant weight in a vacuum drying 
oven at 78° C. 
The sugars, the arabin, and a small part of the xylan used in these 
experiments were purchased from a chemical supply house. The rest 
of the xylan was prepared from rye straw, most of it according to a 
method similar to that used by Schone and Tollens^^ for the prepara- 
22 Hasselbring, H. The Carbon Assimilation of Pencillium. Bot. Gaz. 45: 176- 
193. 1908. 
23 Schone, A., und Tollens, B. Untersuchungen uber die Pentosane der Jute, 
der Luffa, und der Biertreber. Journ. Landw. 49: 21-28. 1901. 
