1883.] Poly desinus complanatus. 391 
fisheries, and brethren of the angle to set their faces against 
all sewage processes in which lime is used, either alone or 
without its equivalent of an acid or acid salt. 
All these processes are to be condemned, from the same 
point of view in which salts or other compounds greedy of 
oxygen are run into the rivers. Ferrous sulphate, or cop- 
peras, ranks among these agents. In like manner any 
alkaline or earthy alkaline sulphide, or any compound from 
which sulphuretted hydrogen can be evolved, should be used 
in the treatment of sewage. Such substances not merely 
rob the water of its oxygen, but a< 5 l as positive poisons. 
IV. POLYDESMUS COMPLANATUS. 
By A. H. Swinton. 
t 'T a late meeting of the Entomological Society of 
London, Professor Westwood stated, as an item of 
Economic Entomology, that the myriapod Polydesmus 
complanatus , L., had been gravely accused in a Sussex news- 
paper of being the cause of the potato disease. 
Observing a paragraph headed “ The Cause of the Potato 
Disease,” in the “ Sussex Gazette,” on the 23rd of last 
March, I was led to inquire into the nature of this startling 
announcement. The writer, Mr. Jesse Page, an agriculturist 
of the sister county, very obligingly took me into confidence, 
and explained that he was under the convitftion that the 
mischief among his potatoes arose from the presence of a 
mysterious insert, whose habits he had been watching these 
thirty years past, and which as yet no one could be found to 
publicly name. The following humorous extract from his 
communication on the subject will sufficiently explain the 
views he had been led to adopt : — “ I got out into my garden 
yesterday for the first time, where I had a man digging 
ground which had been planted with potatoes all the winter. 
I searched for some time, and then I found two inserts evi- 
dently intending to breed there. And this is the beginning 
of my theory. The insert breeds in the old set, and wisons 
it, and causes it to rot prematurely, and when the potato 
dies people examine the haulm to find out the cause.” 
