MARINE BIOLOGICAL STATION AT PORT ERIN. 1138 
There is a tendency, in trying to attain to more exact 
methods in biology, towards arguing and collecting, as if 
organisms were evenly-distributed through the particular 
layer of water or region they inhabit—as if, in fact, they 
were like the salts dissolved in the water, so that one sample 
from a locality ought to be exactly like any other sample. 
This is far from being the case. One gallon or cubic foot 
of water, though, in the main, like its neighbours, may con- 
tain one of the rarer organisms not present in the next gallon 
examined. Consequently, in a net hauled up vertically, 
or in a comparatively small volume of water drawn up from 
a special layer through the hose-pipe, there is considerable 
risk of missing some of the less frequent organisms ; 
while the ordinary tow-net, through which a very much 
creater mass of water passes, will probably contain a more 
completely representative gathering. This is, in the 
main, our objection to the pump-plankton method which 
we tried at Port Erin at Easter on board the fisheries 
steamer “John Fell.” Equal times of working with the 
ordinary open tow-net and with the pump and hose gave 
results, both at bottom and at surface, which were 
absurdly disproportionate. The open tow-net collected in 
the same period many times as much material, and far 
more species than the pump showed. 
Mr. Thompson, in his note on a previous page as to 
Copepoda, has referred to the interesting differences we 
found between surface and bottom (30 fathoms) plankton 
in mid-winter. We hope to continue such observations in 
the deeper water lying between the Isle of Man and Ire- 
land. That, however, can only be done on our 
comparatively rare steamboat expeditions. In the mean- 
time our Curator at the Station has endeavoured, during 
the whole of the past year, to take at least one ordinary 
surface tow-net gathering across Port Erin Bay in the 
