G8 
THE OCEAN WORLD. 
pools, left here and there by the retiring tide, are dragged by nets of 
very small mesh, in which the smaller crustaceous mollusks and small 
fish are secured. 
In the Mediterranean and other inland seas, where the tide i 3 
almost inappreciable, there exist a great number of animals and 
vegetables belonging to tho deep sea, which the waves or currents 
very rarely leave upon the sea shore. There are others so fugitive? 
or which attach themselves so firmly to the rocks, that we can 
watch them only in their habitats. It is necessary to study them 
floating on the surface of the waves, or in their mysterious retirements. 
Hence the necessity that naturalists should study the living produc- 
tions of the salt water even in the bosom of the ocean, and not on the 
sea shore. 
The means generally employed for this purpose is a drag-net, sounding- 
line, and other engines suitable for scraping the bottom, and breaking 
the harder rocks. In a voyage which Milne Edwards made to the 
coast of Sicily, he formed the idea of employing an apparatus invented 
by Colonel Paulin, which consisted of a metallic casque provided with > l 
visor of glass, and consequently transparent, which fixed itself round 
the neck by means of a copper collar made water-tight by stuffing— 8 ’ 
diving-bell, in short, in miniature. It communicated with an air- 
pump by means of a flexible tube. Four men were employed in serving 
the pump, two exercising it while the other two rested themselves- 
Other men hold the extremity of a cord, which was passed over a pulley 
attached at a higher elevation, and enabled them to hoist up the 
diver with the necessary rapidity in emergencies. A vigilant observer 
held in his hand a small signal coftl. The immersion of the diver was 
facilitated by heavy leaden shoes, which assist him at the same time to 
maintain his vertical position at the bottom. M. Edwards made the 
descent with this apparatus in three fathoms’ water with perfect success- 
He was thus enabled to study, in their most hidden and most inacces- 
sible retreats, the radiate animals, mollusks, crustaceans, and annelids? 
especially thoir larvae and eggs, and by his descriptions to contribute 
most essentially to make known the functions, manners, and mode of 
development of certain inhabitants of the sea, whose sojourn au^ 
habits would seem to sequestrate them for ever from our obser- 
vation. 
