MAKINE BIOLOGICAL STATION AT PORT ERIN. 55 



around Scilly and in the Bristol Channel, are largely influenced 

 in their selection of a suitable position by the finding of so- 

 called ' yellow water.' This condition of the sea in the area 

 under consideration arises from the presence of vast shoals of 

 Calanoids — e.g., Calanus finmarchicus, Pseudocalanus elongatus, 

 &c. — which impart a yellowish tint to the surface of the water. 

 The sporadic distribution of such Copepods, moreover, is often 

 somewhat remarkable ; the fishermen state that it is possible 

 at times to observe the entire extent of a ' splat ' of ' yellow 

 water.' The presence of mackerel is generally to be expected 

 in water of this character, but heavy catches are not invariably 

 made in it. — Gr. E. Bullen. The Hertfordshire Museum, 

 St. Albans." 



The following letter to " Nature,"* written at Tobermory 

 some weeks later, records the conclusion of the matter, so far 

 as our summer observations went : — 



"On getting back to Tobermory on Saturday, we found 

 the plankton to be in marked contrast to its condition four 

 weeks ago (see ' Nature,' p. 504). The vast swarm of Calanoids 

 has gone, and there are now no signs of mackerel feeding in the 

 bay. In fact, the change has been noticeable for some days 

 in the seas outside, and we have not been getting lately the' 

 large plankton catches that were usual in the latter half of 

 July. On July 14th a haul of the large surface tow-net, in the 

 open sea off Ardnamurchan, gave such a huge catch of Calanus 

 (about 1,000 c.c.) that we promptly took a second similar haul, 

 and had it cooked as a sort of potted • shrimp ' confection 

 for tea (sampled by ten persons, including the crew, who were 

 much interested to try this new edible ' fish ') ; while on 

 August 11th a haul of the same net, taken at the same spot, 

 gave only a small catch of some 15 c.c, containing very few 

 Calanoids, along with the usual scanty summer zoo-plankton. 



* Nature, August 21st, 1913, p. 636. 



