1920] WILLAMAN—SCLEROTINIA 223 



In order to test the assimilatory power of Sclerotinia toward 

 soluble pectin, a sample of the latter was made by precipitating 

 prune juice with alcohol, reprecipitating twice, and then drying 

 in an oven and grinding. The resultant powder was incorporated 

 in a mineral nutrient medium to the extent of o .4 per cent. With 

 no sucrose added, growth took place, but only about one-fifth as 

 rapidly as when some sucrose was present. Whether this growth 

 was due to the assimilation of pectin, or to sugars adsorbed during 

 the preparation of the pectin, was not evident, since no analyses 

 were made. To test this point quantitatively, another preparation 

 of pectin, from peach, was made. It was decided to follow the 

 product by analyzing for its content of pentosan. Although this 

 is open to many objections, the chief of which is the questionable 

 accuracy of the existing methods of pentosan determination, no 

 other way of studying the fate of the pectin in media appeared 

 feasible. The official (1) phloroglucide method was used. The 

 pectin preparation showed a content of 15.0 per cent furfural, or 

 25.6 per cent pentosan. Schryver and Haynes (7) obtained 

 18.6 per cent furfural in turnip pectin. They had a far purer 

 preparation, however, than the writer attempted to obtain. 



A medium containing mineral salts and 2 per cent of pectin 

 was prepared, and two Erlenmeyer flasks, each with 50 cc. of 

 medium, were sterilized and inoculated with spores of the fungus. 

 Growth was slow but typical. The medium became a gel, due 

 to the coagulation of the pectin by the fungus. After three weeks 

 the colony in each flask had attained a diameter of 3 . 5 cm. (see 9 

 for the writer's method of estimating the growth of this fungus). 

 By this time also the gel had become almost completely liquefied, 

 and the liquid portion gave no precipitate with alcohol. The 

 colonies were carefully removed, freed from the adhering gel of 

 the medium as well as possible, and then the two mycelia and the 

 two media combined for analysis. The results were as follows: 



Pentosan in original media o. 502 gm. 



Pentosan in mycelia of culture 572 0.014 gm. 



Pentosan in residual media o 040 gm. 



Thus a total of 0.054 gm. of pentosan remained in the calture 

 flasks at the end of the period of growth, whereas o. 502 gm. was 



