23 
words, the organic matter in the sea-bottom is mainly derived from 
the benthos formations at the coasts. 
In describing the bottom-soil in Thisted Bredning I remarked that a large 
part of the organic particles in the soil are intensely coloured by Ruthenium-red, 
but not by chlor-zinc-iodine. This indicates that the organic material in the 
bottom-soil consists of pectose and not of cellulose. It appears also, that the 
cell walls of the Zostera leaves likewise contain very little cellulose, 
but on the other hand much pectose. This also indicates that the organic 
matter in the sea bottom is mainly derived from the Zostera belt. A further 
chemical investigation of this condition will perhaps give interesting results. 
The result of these investigations is, therefore, that it is the plants of 
the Zostera belt and not the plankton organisms which constitute the 
principal source of the organic matter in the sea-bottom. Since now 
this organic material, as will be shown later, is the main nourishment for the 
benthos fauna, Lamellibranchs, worms etc., and these again for several of our 
food-fishes, it follows, that it »is certainly this plant, which for a great part 
conditions the fish-wealth of our coasts and attracts the fishes from the open and 
deeper waters into the shallow, enclosed bays and fjords« (C. G. Joh. Petersen, 
I. Ber. f. D. biol. Stat., 1890) — a conception which finds confirmation in these 
investigations. 
8.  Bacteria life in the bottom-deposits.  Bottom-deposits which contain 
organic matter are naturally the dwelling-place for a rich bacteria life. The 
strong smell of sulphuretted hydrogen given off especially by the more muddy bottom- 
samples at once reveals this. We singled out Roskilde Bredning above as the 
place where the largest quantity of organic matter was found. The bottom 
consists of a quite black, strongly odorous mud several meters thick. If we push 
a pole down into the mud we see the air-bubbles rising up to the surface, coming 
obviously from the gases collected down in the mud. Some of this gas was 
collected in a sodawater bottle over water and analysed more closely. Hydrogen 
sulphide does not seem to be present. Å quantity of the gas was driven over 
into a Hempel pipette filled with glass balls and copper sulphate and stood for 
24 hours without any part of the gas disappearing. Further, the gas contained 
very small quantities of oxygen and carbonic dioxide. Some of the gas was 
analysed for inflammable gases, particularly methane; it was mixed in an 
explosion-tube with oxygen and the mixture ignited. The ignition followed the 
equation: 
CEO eo oo 
The quantity of carbonic dioxide formed is thus, measured in volumes, equal to 
that of the methane in the gas. After the ignition, the gas remaining was analysed 
for carbonic acid and found to contain ca. 80?/,. The gas thus contains ca. 809/, 
methane. It should be remarked, that the gas before analysis was cleared of 
carbonic dioxide. 
Certain fermentative processes are thus going on in the mud of Roskilde 
Fjord which lead to the formation of methane. As shown by Omeliansky 
