THE IMPENETRABLE SEA 



naturalist, had used a tow-net to collect plankton from 

 the sea off Cork, as early as 1828, when serving as an 

 army surgeon in Ireland. He was the first to describe the 

 zoea — the crab in its early planktonic stage. He dis- 

 covered the true nature of barnacles a little later, in 1833. 

 He was the first to reveal to the world that plankton are 

 not exclusively tiny creatures that are permanently 

 afloat, but contain many animals from the sea-beds in 

 their early larval stages, and that such sea-bed animals 

 send up their babies in clouds, to be scattered far and 

 wide by ocean currents, just as plants on land send their 

 seeds into the winds for distribution. 



Darwin, eleven years before Miiller, used a tow-net on 

 his voyage in the Beagle — a fact recorded in his Journal of 

 Researches under the date 6th December 1833. T. H. 

 Huxley also used a tow-net on H.M.S. Rattlesnake within 

 a year or so of Miiller's use of the device. It was then a 

 simple enough appliance : a small bag of fine muslin or 

 silk gauze, usually attached to a collecting jar, towed 

 through the water on a line behind a boat. 



Even as early as the middle of the eighteenth century — 

 a hundred years before Miiller's use of the tow-net to 

 catch plankton — two Italian zoologists. Count Luigi 

 Marsigli, pioneer in oceanography, and Vitaliano 

 Donati, naturalist and traveller, had invented and used 

 the naturalist's dredge : a coarse net on an iron frame 

 which brought to the surface from the sea-bed many 

 forms of life previously unknown. 



Four years before Miiller's use of the tow-net, Edward 

 Forbes, who became the recognized pioneer in plank- 

 tonic research, had begun his dredging, in British waters 

 and in the Aegean Sea. All the nets used in these earlier 

 explorations, and all the devices which have developed 

 from them, are man's imitations of the whale's baleen — 

 the flakes or ''blades" of which, with their fine hair-like 

 filaments, are the most eflicient sieve for the collection of 

 planktonic creatures that nature has devised. 



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