400 Froceedings of the Royal Physical Society. 



were taken from the surface in great abundance, so much so 

 in the Antarctic, that their dead frustules made up the de- 

 posit at the bottom, forming a diatomaceous ooze; but at 

 neither of these places had it such an effect in colouring the 

 water, nor was there any offensive odour as when taken 

 in mass in the north by the tow-nets. The herring nets 

 were often thickly coated with this algae, but the phosphatic 

 odour given off was so offensive at times, that the men 

 could scarcely remain at work, and were only able to do 

 so by allowing the nets to run through tubs of fresh 

 water as they were hauled on board. Little heaps of 

 the algse were formed on the deck, as it dropped from 

 the nets. These heaps were to the touch slimy masses, 

 similar in colour to molasses, and the nets from which 

 they fell had to be carefully washed before being again 

 used. 



There can be no doubt, then, that this vegetable matter 

 exercises a very great influence over the herring and the 

 pelagic animals upon which they feed, as very little animal 

 life was found amongst it. In support of my observations, I 

 have received a letter on the subject from Mr W. H. Shrub- 

 sole of Sheerness, with whom I had put myself in communi- 

 cation. He says : — 



" I have often met with Rhizosolenia here in small quanti- 

 ties, and in 1880 or '81 I found that the water of the Thames 

 estuary was crowded with it ; each time I dropped my tow- 

 net over, in a few minutes it was lined with this diatom so 

 thickly as to present a dark velvety appearance, and a very 

 peculiar and powerful odour was emitted. You may be in- 

 terested to know that every year, about May and June, 

 another organism (an alga) abounds in these waters, which 

 fishermen think to be fish spawn ; they say it rots their nets 

 and ropes. It certainly causes such things to feel very 

 slimy." 



There has not been time to carefully investigate and 

 identify all the various organisms taken in the tow-net 

 gatherings. I have therefore merely given the list of the 

 different groups from a few stations, and the localities from 

 which they were obtained, showing where the herring were 



