Absorption of Gold from Colloidal Solutions 
by Fungi. 
BY 
MAUD WILLIAMS, B.Sc. 
I T has been known for some time that colloidal preparations of gold pro¬ 
duced by the addition of tannic acid tend to become mouldy, and that 
the mould, in course of time, removes the metal from the solution (1). 
Upon the suggestion of Mr. E. Hatschek an attempt was therefore made 
to find : 
(a) if the same result could be obtained with solutions prepared by 
Zsigmondy’s method (2) (addition of formaldehyde and sodium 
carbonate). * 
(b) what fungus or fungi could bring about the change.* 
(c) in what region the gold was retained. 
Preparations. 
A series of solutions was prepared by each method, the colours of the 
solutions ranging from red to blue, according to the sizes of the gold 
particles. 
To solutions prepared by Zsigmondy’s method, gum arabic was added 
to serve as a nutrient. 
Spores of Penicillium glaucum , Aspergillus ttiger , and Oidium laciis 
were introduced into separate flasks of the solutions containing about 150 c.c. 
of liquid. Cotton-wool plugs were inserted and the flasks kept in darkness 
at room temperature for upwards of fifteen months. 
As hyphae developed the material was examined microscopically, and 
finally, when considerable dimensions had been attained, the fungus was 
treated with chromacetic fixative or absolute alcohol, embedded in wax, and 
microtomed. 
Observations. 
About one week after the spores were introduced into the flasks, 
hyphae had appeared in the cases of all three fungi. 
Aspergillus niger showed no coloration due to the solution, and quickly 
died. 
[Annalti of Botany, Vol. XXXII. No. CXXVIII October, igxS.l 
