1923] 



CAMP — CITRIC ACID AS A SOURCE OF CARBON 249 



Sclerotinia the situation is a little more uncertain but the fungus 

 would probably make some growth at this acidity. It was prob- 

 able also that the source of nitrogen might make some difference 

 and that when an organic nitrogenous compound, such as a pro- 

 tein, was available growth might occur at higher acidity. For 

 this reason the reaction of the fungi to extracted orange and lemon 

 juice was tried. 



Oranges were peeled, the juice pressed from the pulp, the pulp 

 wet with distilled water and pressed again, and this pressing 

 added to the first. Six hundred and fifty cc. of juice were extracted 

 from 10 oranges in this way, filtered through cotton, and pipetted 

 in 25-cc. amounts into 120-cc. flasks. The P H of the juice was 

 3.8. All the fungi used grew well on this juice. The extracted 

 pulp was put in flasks after being washed until tasteless, a little 

 distilled water added and autoclaved. The P H of the last 

 washings was 4.4. These flasks were inoculated and the fungi 

 grew exceedingly well. The rind was minced up and put in flasks 

 with a little distilled water and sterilized. Organisms 2, 3, and 

 7 grew slowly but eventually covered the rind completely, slowly 

 dissolving the rag. Numbers 4, 5, 6, and 9 grew very rapidly, 

 quickly covered all the pieces, and brought on a destructive, de- 

 composition. 



A lemon- juice extract was made as with the oranges, and for 

 one set of flasks the juice was diluted with an equal amount of 

 water (Solution I), theP H being 2.5. For a second set the juice 

 was diluted with an equal volume of distilled water to which 

 had been added 25 gms. of Bacto c 



II), the P H being 2.5. For a third batch, 100 cc. of 0.48 N KOH 

 was added to 300 cc. of the diluted juice, making the acidity P H 

 3.9 (Solution III). These solutions were pipetted into 120-cc. 

 flasks, 25 cc. per flask, sterilized, and inoculated with organisms 

 2, 3, 4, 5, 6, 7, and 9. At the end of 10 days these were taken 

 down, and the titer and the weight of the mat determined. For 

 the results see table vi. 



From the culture work reported above the fungi would seem 

 to fall roughly into two groups: those that grow fairly well at a 

 comparatively high acidity (P H 2.0-3.0), comprising organisms 

 2, 3, 6, 9, and possibly 11; and a group of those not growing at 



