2 
Journal of Agricultural Research 
Vol. VII, No. i 
species led to the selection of 20 cultures for a comparative test. Two 
forms which could be readily distinguished from the typical black group 
were included: 4030.4, a strain of A . ochraceus , and 3522.30, possibly A . 
violaceo-fuscus of Gasperini. Two other forms, 2580 and 4030.1, have 
differences discoverable readily with the microscope; but most of the 
series shade into each other morphologically. The history of these forms, 
so far as known, follows: 111, A . niger , received in September, 1909, by 
courtesy of Dr. Johanna Westerdijk, Amsterdam, Netherlands; 3534-a, 
A. niger , var. altipes , 3534-b, A . cinnamomeus , 3534-c, A. fuscus , the 
three forms described by Schiemann 1 as mutants from a strain of A. niger 
obtained from Amsterdam and probably identical with No. 111; 142, 
marked A. ficuum , P. Hennings, received from Amsterdam; 2396, from 
Missouri, by Prof. G. M. Reed; 2580, isolated from interior of red pepper 
(capsicum) from Barcelona, Spain; 2469.4, from Delaware, marked Sterig- 
matocystis violacea , by Prof. M. T. Cook; 2657, from soil, England, by 
Miss E. Dale; 2774, from ulcerated human ear, by Dr. A. B. Stout; 2766, 
from fermenting mash, consisting of oak galls from China; 3522.30, pos¬ 
sibly A. violaceo-fuscus of Gasperini from soil, Porto Rico, by Dr. J. R. 
Johnston; 3528.7, from Pittsburgh, the Mellon Institute, by Mr. F. A. 
McDermott; 4049, from sardine paste, Bureau of Chemistry; 3547.254-b; 
from Kansas soil; 4050, from Chinese galls, sent by Eastman Kodak Co., 
4020.33, from soil, Texas; 4030.1, A. carbonarius(?) t 4030.4, A. ochraceus , 
4030.5, from Dr. A. F. Blakeslee, Storrs, Conn. 
Table I gives the chemical results with the strains arranged approxi¬ 
mately in the order of their relative activity in oxalic-acid production. 
Two determinations are given: The direct titration of free acid expressed 
in cubic centimeters of N/10 sodium hydroxid per 50 c. c. of medium, 
and the determination of the oxalic acid as oxalates as found in the 
same amount of medium. 2 
Oxalic acid was first precipitated as calcium oxalate, then dissolved in 
dilute hydrochloric acid and again precipitated. 3 It was redissolved in 
dilute sulphuric acid and titrated with standard potassium permanganate 
to a slight permanent pink. 
The cultures were held two days at 30° C. and for the remaining period 
at 20 0 . 
1 Schiemann, Elisabeth. Mutationen bei aspergillus niger Van Tieghem. In Ztschr. Induk. Abstam. 
u. Vererbungslehre, Bd. 8, Heft 1/2, p. 1-35, 16 figs., 2 pi. (1 col.). 1912. 
s The cultures were grown upon a modified Czapek’s solution with the following composition: 
Water. 1,000 c. c. 
Sodium nitrate. 3 gm. 
Potassium phosphate (KH2PO4). 1.0 gm. 
Magnesium sulphate. o. 25 gm. 
Potassium chlorid. . 0.25 gm. 
Ferrous sulphate... o. 01 gm. 
Cane sugar. 50.0 gm. 
* For a description of the method, see Currie, J. N., and Thom, Charles. An oxalic acid producing Peni- 
cillium. In Jour. Biol. Chem,, v. 22, no. 2, p. 290. 1915. 
