1903.] on Som Problems and MeOiods of Oceanic Research. 363 



acquaintance with them rendered this explanation very improbable. 

 A characteristic feature of the nodules is that when heated in the 

 closed tube they emit a strongly empyreumatic odour and give otf 

 steam which condenses to an alkaline liquid. As my atten- 

 tion was thus early directed to the formation of ochres, I carefully 

 studied every occurrence of them. The organic matter revealed by 

 heating in the closed tube was as invariably present as the ochres, 

 and in the many instances, principally in the Pacific, where large 

 fragments of pumice were brought up from great depths, these masses 

 were perforated by annelids and the holes produced were almost 

 always clothed with a black ochreous lining of the same composition 

 as these manganese nodules, and the pumice in the neighbourhood of 

 the holes was stained of blackish brown colour from the same cause. 



This frequent occurrence of the ochreous formation in connection 

 with the deep sea annelids and the invariable occurrence of organic 

 matter in freshly collected nodules, suggested the connection of the 

 formation of the ochreous deposits with the organic life on the bottom. 

 Ochres, especially hydrated ferric oxide, are essential constituents of 

 the oceanic " red clay." When the sounding tube brings up a sample 

 of bottom from one of these regions, it is quite usual to find that 

 the upper layers of the samples are of a red colour, while the mud 

 immediately below is of a bluish-black colour. As the dredge 

 furnished evidences of the abundance of life in the mud, as the 

 difference of colour of the upper and lower layers of the mud was 

 evidently due to a different state of oxidation of the iron in it, and 

 as the water in contact with the surface of the mud always showed a 

 deficiency of oxygen, there was little diflSculty in concluding that the 

 existence of animal life in the mud had some effect in modifying its 

 chemical composition. 



When a freshly collected sample of submarine mud is carefully 

 washed with a jet of water, until the finer flocculent particles are 

 removed, the mud which remains is in the form of elongated casts of 

 ellipsoidal form. Pressure with the finger breaks them up into 

 flocculent particles, which can be washed away with the jet of water, 

 leaving still some ellipsoids. By continuing this treatment, finally 

 all the flocculent matter can be washed away, but the ochreous 

 deposits thus freshly collected and carefully examined are always 

 found to be made up of these ellipsoids which are nothing more nor 

 less than coprolites. The animals, which live in abundance in 

 the mud, live by passing it through their bodies and extracting from 

 it what nutriment they can. The trituration of the mud in the 

 interior of the animals and in contact with living organic matter 

 reduces the sulphates of the sea-water to sulphides. These, in 

 contact with the ferric oxide of the mud, reduce it to ferrous sulphide 

 with separation of sulphur. Hence the mud not immediately in 

 contact with the water has a bluish-black appearance. When it 

 comes in contact with the water which contains free oxygen, the 

 ferrous sulphide is oxidised and the surface layer becomes red. If 



