41 



" The Noctilucse, which cause the phosphorescence in the 

 sea, are diatom-feeders, and may be caught in large quantities 

 in a fine gauze towing-net. 



" The Ascidians, found attached to oyster shells and stones 

 from deep water, have yielded excellent gatherings. 



" The Salpae, often noticed in warm, latitudes floating on 

 the surface of the sea, and assuming chain and other like 

 forms, ought to be bottled up for examination. These Salpae 

 are well-known diatom-feeders. 



" Deep sea soundings ought to be preserved, especially from 

 great depths, and are often exclusively diatomaceous. Sea- 

 weed from rocks ought to be preserved, especially the smaller 

 species, and if covered with a brown furriness, so much the 

 better. 



" Very rare species have been found in immense quantities 

 in the Arctic and Atlantic regions, by melting the 'pancake 

 ice> which is often found discoloured of a brown tint in con- 

 sequence of the great numbers of these minute beings. 



" The sea is often observed to be discoloured by brownish 

 patches. The discoloured water (or 'spawn,' as it is called) 

 should be collected, filtered through cotton-wool, and the 

 brown residue preserved. 



" When a fine impalpable dust is observed to be falling at 

 sea, it ought to be collected from the folded sails and other 

 places where it lodges. This may yield Diatomacese which, 

 from the method of collecting, would be highly interesting to 

 examine. 



" The roots of the various species of Mangrove (Rhizophora) 

 which form impenetrable barriers along the salt-water rivers 

 and estuaries in the tropical parts of Africa, Australia, the 

 Eastern Archipelago, &c., are found frequently covered with 

 a brown mucous slime, said to be very rich in Diatomaceae. 



" When the Diatomacese are collected from any of the 

 above-mentioned sources they may be at once transferred to 



