134 Potter . — On the Occurrence of Cellulose in the 
duramen-decoction both phloroglucin and thallin sulphate gave the 
characteristic colours, but somewhat faintly. Phenol-HCl gave no colour- 
reaction in either case. 
Flasks sown with Penicillmm. After twenty-three days several 
colonies had developed in the alburnum-decoction and produced conidia, 
but in the duramen-decoction no signs of colonies could be detected. 
With phloroglucin and thallin sulphate the ether-extracts gave very distinct 
reactions in the case of the duramen-decoction, but with the alburnum 
the colour was very much fainter. Phenol-HCl gave no colour-reaction 
in either case. 
The control flasks were next examined (after twenty-five days). The 
ether-extracts from both the alburnum- and duramen-decoctions gave 
the characteristic colours most distinctly with both phloroglucin and 
thallin sulphate, but not with phenol-HCl, again showing that the vanilin 
is extracted but not the coniferin. 
This experiment was repeated with decoctions of the alburnum and 
duramen from the sixty years-old Warwickshire Oak, using o, gram, of 
wood to each ioo c.c. of water. The results were in all respects confirma- 
tory of those just described. 
These experiments show very clearly that the substance extracted 
from the Oak-wood by water, which reacts to phloroglucin and thallin 
sulphate, is destroyed by certain Bacteria and in some measure by Peni- 
cillinm. Both B. subtilis and the Bacteria which developed naturally 
in the extract, grew vigorously in the alburnum-decoction and destroyed 
the substance extracted from the wood. Bacteria being thus able to 
destroy the ‘ lignin ’ substances, this fact explains why the colour-reaction 
to phloroglucin was no longer given in the cold-water extract after eight 
days (p. 132). 
It is further demonstrated that the alburnum is more readily acted 
upon by these organisms than the duramen. This is an important 
consideration, and suggests that the duramen contains substances not 
possessed by the alburnum which are unfavourable to the growth of Fungi 
or Bacteria. 
These investigations throw some light upon the natural decay of 
timber, and suggest that one of the initial stages of decay is the extraction 
by water of some substance or substances from the xylem ; by this process 
the cellulose is exposed, and it is then liable to be attacked by vegetable 
saprophytes. The fact that these organisms do not grow so readily in the 
watery- extract from heart-wood is suggested as a reason why the heart- 
wood is more durable. 
In criticizing Singer’s work Czapek considers his conclusions to be 
erroneous. He, however, makes no mention of repeating his experiments ; 
while my results support Singer and prove that he was right in attributing 
