SEA-FISHERIES LABORATORY. 



163 



microscopically in the laboratory — so no loss of material was 

 possible through straining or transferring from one vessel to 

 another. 



The first four series (six in each) were taken in April 

 during the time of the ordinary mixed early spring plankton 

 before the phytoplankton maximum ; the next series, in May 

 (four hauls), was just at the time of the Rhizosolenia maximum 

 and shows a typical phytoplankton ; the August series (four 

 hauls) shows a scanty summer zooplankton ; and the last 

 series, in September (four hauls), shows again an abundant 

 phytoplankton of autumn Diatoms and Dinoflagellates. 



Two out of the thirty-six bottles were unfortunately broken 

 in transit from the Isle of Man, so that the total number 

 examined and now reported on is thirty-four, as follows :— 



April 3 



„ 13 



May 25 



Aug. 7 



Sept. 16 



Fathoms. 



Hauls. 



8 



6 



20 



..5 



20 



6 



8 



5 



20 



4 



20 



4 



20 



4 



Average. 



0-20 c.c., mixed plankton. 

 0-56 c.c., „ 

 0-52 c.c., „ 

 0-48 c.c., 



16-125 c.c., phytoplankton. 

 0-50 c.c., zooplankton. 

 6-10 c.c., phytoplankton, etc. 



The nature of the plankton in each series was more or 

 less what was to be expected in the locality at that time of year, 

 and the volumes of the catches were also fairly characteristic 

 of the season. The apparent uniformity in the successive 

 catches of each series was obvious at the time of collecting. 

 It seemed to the eye to be the same catch that was emptied 

 from the Nansen-bucket into the bottle of formaline time after 

 time throughout a series. And this apparent uniformity of 

 volume is in most cases confirmed by the careful measurement 

 made afterwards in the laboratory — for example, the six 

 successive hauls from 8 fathoms on April 3rd all measure 

 0-2 c.c, four out of five of those from 20 fathoms on April 6th 

 are 0-6 c.c, and all four on August 7th from 20 fathoms measure 

 0-5 c.c The remaining four series show some variation, but 



