498 TRANSACTIONS OF SHCTION D. 
has necessitated an immense organisation. Some eight or ten steamers are 
employed making periodic voyages, under the direction of trained men of 
science. Enormous numbers of temperature-readings, investigations into 
the speed and direction of currents, and chemical analyses of sea-water have 
been recorded, and thousands of samples of the bottom, of the animals and 
plants living thereon, of fish in all stages, millions of fish ova, have been 
collected and accurately determined. To work up such an amount of 
material has occupied the attention of a large number of naturalists. Each 
country has at least one large laboratory devoted to this work, and their 
results are co-ordinated and generalised by the central bureau. The 
English part of the work was entrusted by the Lords of the Treasury to the 
Marine Biological Association, and has been carried out under the direction 
_of Dr. E. J. Allen and Professor Walter Garstang at our laboratories at 
Plymouth and Lowestoft. 
Although all the ten countries are working upon what is, broadly 
speaking, a common plan, each has had its own special problems. In 
addition to carrying out the broad outlines of an international scheme, they 
have specialised along lines indicated by their own needs, and have attacked 
problems whose solution affected their own special food supply. Thus 
Norway, where the old open fishing-boat is being replaced by the modern 
decked trawler, has especially studied the cod and the saithe, the haddock 
and the herring, and has devoted much time and labour to the discovery of 
new fishing grounds, and has successfully done this along the Norse coast, 
in the Arctic circle, and on the banks between the Faroe Islands and 
Iceland. They have further established a trade in Pandalus borealis, 
allied to the prawns, which are taken in the deep waters off Norway, and 
are now to be bought in most fishmongers’ shops in Great Britain. 
Ina similar way the Danes have tracked the eels as they leave the 
estuaries of the great rivers of Central Europe across the North Sea to the 
deep Atlantic off the West of Ireland, just beyond the 1000 fathom line. 
In these depths they spawn and the resulting larval form, the Lepto- 
cephalus, long thought to be a separate genus, lives there for a while, until, 
gradually changing into an elver, it retraces by some mysterious instinct 
its parents’ path across the ocean and regains the fresh-water rivers which 
those parents had left. 
The English share of the investigation is limited to that part of the 
North Sea which lies south of the latitude of Berwick, and for the most 
part to the western half of these seas and to the English Channel ; the 
latter, as we shall see, is a very important area. The work, so far as it has 
been specialised, deals, in the North Sea, largely with the plaice, with the 
food of fishes generally, and with the character of the deposits forming 
the sea-floor, with the creatures growing thereon. In the Channel the 
Iinglish worker is entirely responsible for the study of the hydrography of 
the water, which, entering the North Sea through the Straits of Dover, 
contributes greatly: to its mass. ¥ 
As a result of Professor Garstang’s investigations, an important 
spawning ground of the plaice has been located in the southern bight of the 
North Sea; the migration of both sexes has been traced to these grounds 
‘on the advent of the spawning season, and their return to their feeding 
grounds in the spring has been followed. During the spawning season it 
is usual to catch more males than females on the spawning grounds, possibly 
because at this time the female is inert and elusive, whilst the male is 
unusually active. 
‘The course of the ova has been traced, chiefly by the Dutch investigators, 
as they drift towards the shallow fringe of coastal water, by far the greater 
number along the continental coast. Here the young fry grow up, and, 
after attaining a certain size, they leave the shallow coastal waters for the 
deeper seas off shore. Comparatively few of these, however, reach the 
