2 BE. Q. H. FOWLEE— BISCATAN PLANKTON : 



fauna is only possible by a comparison of numerous hauls taken at all depths in the same 

 area at aboiit tbe same date. 



The special problems, with reference to which the hauls were planned, were (1) the 

 vertical movement of the Epiplanktou in relation to time of day, and, if possible, to such 

 other varying conditions as rain, wind, and swell ; (2) the presence (or absence) in deep 

 colder water of organisms known to occur at the surface in higher latitudes, but not 

 represented in the warmer surface-w^aters of the Bay of Biscay. Until the Ileports on 

 the various groups of animals are finished, it will be impossible to say how far the 

 attempt on these two problems has been successful ; but I venture to think that a glance 

 at the table of hauls below (pp. 8-10) will show that a serious attempt has been made to 

 attack them. In this first communication those workiug data of the cruise are publislied 

 which will make subsequent Keports intelligible. 



The methods of collection employed were : (1) ordinary open tow-nets (about 

 20 inches diameter, except net 180 which w^as 12 inches in diameter) towed by the 

 ship's drift at the surface and at depths of 25, 50, 75, and 100 fathoms; (2) the opening 

 and closing Mesoplankton net which had been previously used with success by myself in 

 the Pseroe Channel, and by the Dutch ' Siboga ' Expedition in the East Indies * ; (3) a 

 Mesoplankton trawl, differing only from the latter in having a 4i-foot-square mouth, and 

 a bag made of pilchard-netting, 9 feet in length, but with the same arrangements for 

 opening and closing ; (4) at the close of the cruise, open tow-nets bent on to a wii*e rope 

 at intervals between 100 and 350 fathoms, after the serial method in use on H.M.S. 

 ' Challenger,' for comparison with what I regard as the more certain method of a closing 

 net. So far as I have observed, while the serial method brings on deck a very much 

 larger quantity of material, its condition is often not so good as that from the closing nets. 



On the question of the nets, some of my results may perhaps prove of use to other collectors on 

 hoard ship. 



(1) With hauls at the actual surface (since a long line is necessary to let the net go clear of the ship's 

 refuse, and clinkers and potato-parings do not improve the Plankton) hemp rope and a float where the 

 Ijridles of the net are attached to it, give the best results : even a fine wire has a tendency to sink the 

 net to an uncertain depth, and wet cod-line cuts the hands painfully when hauled. With deeper Epi- 

 plankton hauls, down to 100 fathoms a small hand-wiuch and fine wire rope with a 19 lb. lead at the 

 end gave excellent results ; but even with this weight the nets have a tendency to stream upwards and 

 away from the vertical, and in drifting before a strong wind a net at the end of a 100-fathom wire may 

 have towed anywhere between 100 and 70 fathoms. If the angle made by the visible wirCj which may 

 be 45° in a strong drift, were constant for the whole length of the wire, then 



the 100-fathom mark would be at 70 fathoms, 

 „ 50 „ „ 35 „ 



In using two nets at a time on the wire, and a 20 lb. lead, it is safer, except in a flat calm, to bend the 

 nets on, not at the 100, 75, &c. marks, but at from 5 to 10 fathoms below these marks ; it is better to 



* ' Siboga ' Expeditie : Introduction et Description de I'ExpeditioD., par Max Weber, p. 11. I may perhaps be 

 pardoned for remarking that Prof. Weber speaka well of the net. 



