198 



TRANSACTION'S LIVERPOOL BIOLOGICAL SOCIKTY 



Date. 



us. 27 ... 



Average per 

 9-5 



Haul, 

 c.c. 



Da 



Sept 



Oct. 



Nov. 

 Dec. 



■41 



be. 

 20 .. 



Averag p t 



5 



Haul 



c.c. 



„ 28 .. 



3 



2] 



r:> 





., 29 .. 



8 



23 



8-5 





„ 30 .. 



2 



24 .. 



s 





„ 31 .. 



2 



26 . . 



3 





ept. 2 



3 



2 



27 .. 



3 





3 .. 



28 .. 



7 





4 .. 



2 



30 .. 



(i 





5 .. 



1-5 



1 .. 



1-5 





6 



2 



9 .. 



7 





9 .. 



6 



14 .. 



11-5 





•„ 10 .. 



2 



24 .. 



7 





11 .. 



2-5 



4 .. 



11 





., 12 .. 



4 



8 .. 



6 





„ 13 .. 



3 



1G .. 



1-5 





„ 14 .. 



45 



25 .. 



25 





16 .. 



8 



12 .. 



1 





17 .. 



4 



20 .. 



1 





18 



7 



7 



23 .. 



1 





„ 19 .. 



30 .. 



If) 





From this list and the unsmoothed curve shown below 

 (fig. 8) it is seen that the greatest bulk of plankton in the 

 water is in April, when the total catches in the day 

 reached an average of 51 c.c. per haul. Other lesser 

 elevations are seen in June with 20 c.c, and August with 

 25 c.c, 



The catch in some individual hauls runs a great deal 

 higher than these averages, the top score being the Nansen 

 net on April 4th, with 164'5 c.c. 



The spring maximum in the amount of the plankton 

 is clearly due to a great and sudden increase in the 

 amount of Diatoms present. The other rises seen later in 

 the year, as in June, August, and to a slighter extent in 

 October, are less marked, and are less clearly due to one 

 cause. 



Seasonal Variations in the Plankton. 



The above remarks indicate, what has in fact long 

 been recognised, that the amount of plankton varies to 

 some extent with the season. 



We shall now reproduce some of our Forms giving the 



