28 PROCEEDINGS OF THE 



Whilst I was taking these samples in the open sea, almost daily, 

 from the yacht, Mr. Douglas Laurie, with a crew of students from 

 the Biological Station, simultaneously took similar samples inside 

 Port Erin bay in comparatively sheltered water. In 23 working 

 days I find that we took in all 276 samples, an average of 12 

 per day. It will be readily understood by anyone who has carried 

 on such work continuously, with varied weather, that it was a 

 busy time ; and that on some days we were fairlj'- wet, without 

 any time to get cold, from moi'ning till night. So much practical 

 work could only be carried on with the wilhng help of several 

 assistants. All on board the yacht helped in various ways, but I 

 must thank especially Mr. Buchanan-Wollaston who assisted me 

 in working the nets, Mr. Chadwick who preserved most of the 

 material in the laboratory at the end of each day's work, and 

 Mr. Andrew Scott, A.L.S., who has systematically examined the 

 samples for me. A detailed account of these gatherings will appear 

 elsewhere ; I propose at present to discuss only some of the more 

 obvious features of the series — partly from my own records made 

 at the time of collection and partly from Mr. Scott's notes. 



At each station, after taking the bearings and the depth, we first 

 lowered two vertical nets, the Petersen-Hensen and the Nansen, 

 to a depth of 20 fathoms, pulled them up slowly through 10 

 fathoms, and then closed them by " messengers " run down the 

 line. This gave us samples, taken vertically with these two very 

 dilferent nets, of the organisms present in the w^ater between 10 

 and 20 fathoms. After that three ordinary horizontal open tow- 

 nets exactly alike in all respects (size, shape, mesh, age) were put 

 over — one (A) with a weight attached was allowed to sink to a 

 depth of about 10 fathoms, from which it gradually rose as the 

 ship went slowly ahead ; while the other two (B and C), un- 

 weighted, remained continuously at or just under the surface and 

 worked side by side, like a pair of sharks or porpoises swimming in 

 our wake. Tliese last two nets ought, if there is any uniformity 

 whatever in the plankton even in the most limited areas, to give 

 similar results, and of course they did so in most cases. My 

 purpose in taking the two similar surface nettings side by side 

 was to show this, and also to test the reliability of the sample ; 

 for I would only consider it a trustworthy sample when these two 

 nets agreed in their evidence. Where, under the circumstances 

 stated above, the gatherings differed notably, there must have been 

 some accident in the working of the nets or some abnormality in 

 the distribution of the plankton, such as, no doubt, will sometimes 

 be encountered when traversing the edge of a swarm of gregarious 

 organisms ; and it is important to get some evidence as to how 

 frequently such accidents or abnormalities may be met with. 

 Por example, on April 2nd, at Station III., I find that the two 

 surface-nets used together gave 17 cc. and 42*5 c.c. of material 

 respectively; on April 9th, at Station I., 2-5 and 8 c.c. respectively; 

 and on April 24th, at Station II., they gave 7 c.c. and 15 c.c. 



