982 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
. 
30th, making an average of 5,228 per haul for the month, 
taking both nets into consideration. 
When compared with last year’s curve, the above 
record shows that in spring the usual great increase in 
number of Diatoms was much later in 1908. The 
numbers are lower in January, February and March, and 
the sudden rise does not begin until further on in April, 
although it afterwards, late in April, when Diatoms were 
almost absent in 1907, attains to a much greater height. 
But perhaps the most remarkable feature of this year’s 
phyto-plankton is the enormous increase in May, reaching 
nearly three millions per single 15 minutes’ haul across 
the bay at the end of the month. In fact, with occasional 
drops, the number is up in the millions for a great part of 
the two months May and June—a period when the 
numbers were not at all high in 1907. 
From the middle of July onward there is no great 
difference between the two years. This year, again, in 
August Diatoms are practically absent, and again there 
is a second, but lesser, late autumn maximum. This 
rise is, however, in 1908 not until the third week of 
October, after which the figures keep low, under 10,000 
per haul (with one rise to 14,500), throughout November 
and December. Both the spring and the autumn maxima 
were thus much later than in 1907, and the numbers of 
Diatoms obtained in individual hauls were not nearly so 
great at either time of year—reaching to not quite 
150,000 in autumn this year as against 13,000,000 and 
16,000,000 in 1907. 
Just as it has been found necessary to analyse the 
total plankton into its constituent groups, since Diatoms 
and Copepoda, for example, do not reach their maxima 
at the same season, so it may in some groups be necessary 
to analyse the totals still further and consider the 
ys. 
