532 Williams.—Absolution of Gold from 
Penicillium and Oidinm both showed faint red, purple, or blue in the 
hyphae, according to the colour of the solution used. 
From this time onwards growth of the fungus was always much quicker 
in the tannin preparations than in the Zsigmondy solution. 
Oval or circular masses formed, sometimes on the surface, sometimes 
entirely submerged. Deeply tinted central regions developed with paler 
peripheral parts. As the gold accumulated in a region the colour gradually 
became blue. Material had to be cultivated for periods of four to nine 
months before the patches were sufficiently large to be embedded. For 
each method of preparation it was noticed that colour appeared in the 
hyphae more rapidly in the case of red solutions than in the case of blue. 
This point is of interest since it is known that the red solutions contain 
smaller particles ( 3 ), and diffuse more rapidly than the blue ( 4 ). 
After material had been kept for ten to twelve months it was common 
to find the conidial stage again reached. Great development of intercalary 
spores was characteristic of most of the Oidium lactis cultures. 
In no case was precipitation of the gold in the flasks observed, and there 
was a tendency for the liquids themselves to become alkaline. Thus six 
specimens prepared in December, 1915, and tested in October, 1916, all 
showed action on red litmus paper, although they had been prepared by 
means of tannic acid. 
Controls. 
t. To find whether any of the observed colouring was due to the 
influence of tannic acid or gum arabic, material was grown upon these 
substances. 
2. The alcohol, xylol, and oil of cloves used in the microscopic 
preparations were each added to separate portions of the solutions. No 
precipitation was produced. 
The chromacetic fixative, when added in large amounts to specimens 
of the solution, produced a brownish precipitate, but this was quite unlike 
any colouring observed in the preparations. 
3. Deeply coloured patches of fungi were soaked in chlorine water, 
with the result that the gold could be completely removed. 
4. Cultures of the fungi used were grown upon tannic acid and gum 
arabic, then killed by soaking in absolute alcohol, well washed and added to 
solutions in order to find whether retention of the gold would result. 
Examination of Sections. 
A striking feature of all sections was the small amount of protoplasm 
in the hyphae. In the alcohol preparations the plasmolysis of the proto¬ 
plasm was helpful in determining the region of retention as the specimens 
