132 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
THE PLANKTON ON THE WEST COAST OF 
SCOTLAND IN RELATION TO THAT 
OF THE IRISH SEA. 
By W. A. Herpman, F.R.S., anp Wm. RippeEtu, M.A. 
In the ‘‘ Intensive Study ”’ of the plankton of the Irish 
Sea that has been carried on during the last four years, 
mainly from the Port Erin Biological Station as a 
centre, we have determined at least the main outlines of 
the characteristic seasonal variations in the leading 
groups of animals and plants composing the plankton 
in that district. Though individual years may be 
‘“early’’ or “‘late’’ or have other special features, as 
surely as the vernal equinox comes round so surely do 
we find the amount of the plankton in a “‘ standard ’’* 
haul increasing in amount and becoming more markedly 
phyto-planktonic in character, until some time in April 
or early May the spring phyto-plankton maximum is 
reached, when the sea is found to be swarming with 
Diatoms and the hauls are much larger in volume than 
is usual throughout the remainder of the year (see 
Table, p. 174, column D = 100 c.c.). Then, after a 
few weeks, some time during May and June the phyto- 
plankton gradually dies away and is replaced by the 
zoo-plankton which is characteristic of the summer 
months (Table, col. EK). Although, except in the case 
of occasional local or temporary swarms, this summer 
zoo-plankton is not nearly so abundant as the spring 
phyto-plankton, still it is equally characteristic and 
regular in its appearance. 
* Made with a standard net, in a standard time and according to the 
standard manner. ; 
