1895 - 96 .] Mr Irvine and Dr Murray on Marine Muds. 39 
by excess of carbonic acid present in these muds, sulphuretted 
hydrogen being set free. 
With regard to the fermentation of Cellulose and its products, we 
leave Professor Hartley’s conclusions as they stand, having no 
criticism to offer, as the subject has not been especially studied by 
us ; and we would, in conclusion, remark, that the chemical changes 
occurring and recurring in such an exceedingly complex compound 
as is represented by oceanic blue mud, cannot be written down even 
by the most complicated reactions or formulte, but which, on the 
other hand, might be a simple matter if the organic remains present 
in these muds were only cellulose, as is represented in Professor 
Hartley’s paper. A principal object of our paper on the blue muds 
was to explain how vast chemical reactions were continually taking 
place between the sea-water salts and ferruginous muds or clays 
and decomposing organic matter, one of which was the abstraction 
from the sea and storing up of sulphur in a stable condition in 
muds which, in time, become rocks, containing that element 
generally in the form of sulphide of iron. 
Later knowledge compels us to admit that the changes in these 
fermenting blue muds may be wholly dependent on the influences 
of bacteria. 
