46 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Appendix A. 



Notes on Special Plankton Investigations. 

 By Andrew Scott, A.L.S. 



In addition to the tow-nettings from Port Erin Bay 

 taken at intervals by Mr. Chadwick, an interesting series 

 of special samples of the plankton was made by Professor 

 Herdman from the s.y. " Madge," between July 22nd and 

 September 17th. This series was collected by various 

 kinds of nets simultaneously, at depths from zero to 

 twenty fathoms, between Turby Point and the Calf of 

 Man, and was represented by 74 gatherings. It is only 

 proposed to give a few of the more striking results here, 

 as a detailed account will be presented later to the 

 Biological Society. It might be mentioned, in passing, 

 that the nets comprised ordinary tow-nets, old and new, 

 worked side by side, a small Apstein net used at the 

 surface, a Hensen-Petersen self-closing net towed at a 

 depth of 5 to 7 fathoms and then closed before being 

 drawn to the surface, and a weighted ordinary tow-net 

 worked at a depth varying from 5 to 15 fathoms. 



On measuring and examining the material, it was 

 found that, although the gatherings were taken in equal 

 periods of time, in a very limited sea-area, there was no 

 uniformity either in quantity or kind of organisms 

 captured. Some days the surface net contained a larger 

 quantity of material than the deep one, and on other 

 days there was more in the deep net than in the surface 

 one. The old surface net which had been used many 

 times previous to this special work appeared to fish better 

 than the new one, which had not been used before. The 

 Apstein net invariably captured fewer organisms than 

 the ordinary net. 



