Lewis Knudson 163 



filter was prepared in the usual manner, as employed in quantitative chem- 

 ical analysis, and filtration was made by means of the Gooch funnel with 

 suction. The original solution was first decanted into the Gooch crucible. 

 The felt was then washed in the flask four or five times with distilled water at 

 room temperature; or, if gallic acid had been precipitated, warm water 

 was used. The washing of the felt continued until the wash water was per- 

 fectly clear. The felt was then placed in the Gooch crucible, the flask aga;in 

 washed and the wash water poured into the Gooch crucible. The advan- 

 tages of the method consist in the rapidity of the filtiation and the accuracy 

 which results from the thorough washing, which latter is important when the 

 culture solution is to be analyzed and absolute weight of mycelium is to be 

 obtained. It is an especially accurate method of securing all the fungous 

 mycelium, and by exercising a little care there is no noticeable loss of spores. 



IV. TOXICITY OF TANNIC ACID FOR CERTAIN FUNGI. 



In the literature of tannic acid fermentation only two organisms 

 are mentioned as possessing the property of effecting this fermen- 

 tation; these are Aspergillus niger and Penicillium glaucum. In 

 order to determine whether other organisms are capable of effecting 

 the transformation, a considerable pumber of filamentous fungi 

 were carefully tested with respect to their ability to grow in tannic 

 acid solutions. 

 _ As a nutrient medium a bean decoction was made by boiling 1 

 diter of laboratory preserved beans with a liter of tap water. The 

 juice was then filtered off and diluted to 2 liters. With this decoc- 

 tion as a solvent, four concentrations of tannic acid were made; 

 namely, 0.25 per cent, 2 per cent, 5 per cent and 10 per cent. Test 

 tubes were employed as culture vessels, to each of which were 

 added 10 cc. of the solution. Small wads of filter paper were 

 added to afford a solid substratum. The tubes were prepared in 

 duplicate, sterilized, inoculated and kept at room temperature. 

 They were examined at intervals and the final observations made 

 at the end of two weeks are recorded in table A. 



It is especially noteworthy that the 5 per cent permitted the 

 growth of only one-third of the organisms, while in the 10 per cent 

 solution only Aspergillus flavus; Aspergillus niger and Penicillium 

 sp. are able to grow. A separate experiment indicated that 

 Aspergillus oryzae could withstand 10 per cent tannic acid. 



An experiment was also made to determine if any of these organ- 

 isms could utilize tannic acid as a source of carbon. Solution B 

 with 1L6 grams of tannic acid per 100 cc. of solution was used. 



