184 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
been carried in by currents to where they are found. A 
few individuals may invade a _ neritic area either 
normally or accidentally (that is, as the result of 
unusual influences), and if they find suitable conditions, 
may reproduce actively and give a character to the 
plankton. This may be the case in localities like Loch 
Hourn and Loch Nevis, where there is a mixed plankton, 
appearing in some hauls to be rather more neritic, and 
in others more oceanic, in character. And it is only in 
this way, by supposing that the oceanic organisms 
having gained access to a suitable locality may there 
reproduce in quantity, that we can account for the 
presence of an oceanic element in an inshore loch or other 
locality closed in from the ocean by a sea containing 
neritic plankton. 
If the attempt be now made to explain the plankton 
distribution on the West of Scotland in terms of hydro- 
graphic movements, it must be supposed that the 
Atlantic water gains access more freely in summer to the 
Clyde sea-area, and to the region North-East of Skye, 
than to the large area of the West Coast lying between. 
If an oceanic current reaches the Clyde sea-area, inside 
Cantyre, and another flows in round the North of Skye, 
while little or no such water invades the seas to the 
north and south of and around Mull, such a_ hydro- 
graphic distribution would go far to explain what we 
have observed in the distribution of the plankton. 
Now Bassett* has shown that Atlantic water from 
the south flows slowly through the Irish Sea and out to 
the north, and Knudsent has also stated that there is a 
constant flow of water up the Irish Sea to the West Coast 
of Seotland. If this current from the Irish Sea conveys 
* Report Lancash. Sea-Fish. Lab,, for 1909, p. 154. 
+ Publ, de Circonst,, No, 39. 
