[Vol. 10 



294 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



(3) After a mat had been grown on dextrose, free citric acid 

 was utilized readily by Penicillium stoloniferum , P. sp., and Asper- 

 gillus sp., and somewhat less readily by Sclerolinia Libertiana. 

 Free citric acid was used slightly or not at all by mats of Diplodia 

 natalensis, Phomopsis Citri, Alternaria Citri, Alternaria sp. and 

 Penicillium digitatum. The response of the fungi in this respect 

 was coordinate with their tolerance of the hydrogen-ion concen- 

 tration. 



Studies have been carried out with Penicillium sp., Penicillium 



stoloniferum, Penicillium digitatum, Aspergillus sp., Diplodia 

 natalensis, Alternaria Citri, Alternaria sp., Phomopsis Citri, and 

 Sclerotinia Libertiana on a dextrose and a dextrose-citrate medium, 

 and curves for the growth, trend of Ph, "loss of dextrose," "loss 

 of carbon," etc., are given for these fungi. 



Acidic and alcoholic products were found to be formed under 

 unfavorable environmental conditions, that is, lack of Oi, un- 

 favorable P H , etc. 



It has been pointed out that tolerance or utilization of free 

 citric acid is probably not an important factor in the specialized 

 parasitism of such fungi as Phomopsis Citri, Pejiicillium digitatum, 

 Alternaria Citri, Alternaria sp., Sclerotinia Libertiana, and Diplodia 

 natalensis, but that it probably is a factor in the destructive 

 rotting of injured fruit by numerous fungi which cause this 

 final collapse, and that under suitable environmental conditions 

 Penicillium stoloniferum, Penicillium sp., and Aspergillus sp. 

 would probably come in the latter category. 



It is with great pleasure that the writer takes this opportunity 



for thanking Dr. B. M. Duggar for invaluable aid and advice 



in the prosecution of the work here reported; he also wishes to 



thank Dr. P. A. Shaffer of the Medical School of Washington 



University for aid in connection with the chemical work, and Dr. 



George T. Moore for the privileges and facilities of the Missouri 



Botanical Garden. 



Graduate Laboratory, Missouri Botanical Garden. 



Bibliography 



Amberg, S., and McClure, W. B. ('17). The occurrence of citric acid in urine 

 Am. Jour. Physiol. 44: 453-402. 1917. 



i 



