PLANKTON 243 



plankton. On one occasion in mid-ocean I encountered a 

 good example of a swarm of a very minute organism so 

 abundant as to colour the water. In the Southern Ocean, 

 between the Cape of Good Hope and Australia, the sea was 

 noticed one afternoon to be blood-red in the curl of the 

 waves where the sunlight shone through. I pointed it out 

 to several members of the British Association party on 

 board, and all agreed that it was most striking. My tap-net 

 a little later showed that the colour was due to a minute 

 red Peridinian, which must have been present in enormous 

 profusion over a limited area in the open sea where there 

 was no recognized current carrying special conditions — and 

 cases are on record of swarms of this or an allied form not 

 only colouring the sea locally, but also causing such a 

 pollution of the water as to result in widespread death of 

 larger marine animals so as to cause a nuisance when cast 

 up on the Austrahan coasts. In the recent literature of 

 the subject there are many other similar cases of marked 

 irregularity of even the more minute plankton in the open 

 ocean, such as Ove Paulsen's observation that the sea 

 to the east of Iceland in July was blood-red for days from 

 the presence of Mesodinium pulex, and also his record of 

 very unequal distribution in the open Atlantic Ocean near 

 the Faroe Bank — the quantity of plankton being very 

 much greater in one haul than in the previous one. But 

 to my mind the chart -diagrams of the quantitative plank- 

 tologists themselves tell in the same direction ; for example, 

 the one giving the results of the Plankton Expedition in 

 the Atlantic shows a very marked irregularity, not only as 

 between arctic, temperate, and tropical waters, but also 

 almost day by day in most parts of the ocean traversed. 



In aU these cases, no doubt it may be said the plankton 

 results were different because the conditions were not 

 similar ; but it is surely not justifiable to say that in the 

 open sea the plankton must be evenly distributed because 

 the conditions are constant over large areas, and then, 



