28 CHARLES DARWIN 



referred to, which are frequently dispersed throughout the 

 water, for they are not sufficiently abundant to create any 

 change of colour. 



There are two circumstances in the above accounts which 

 appear remarkable : first, how do the various bodies which 

 form the bands with defined edges keep together? In the 

 case of the prawn-like crabs, their movements were as 

 coinstantaneous as in a regiment of soldiers ; but this cannot 

 happen from anything like voluntary action with the ovules, 

 or the confervae, nor is it probable among the infusoria. 

 Secondly, what causes the length and narrowness of the 

 bands? The appearance so much resembles that which may 

 be seen in every torrent, where the stream uncoils into long 

 streaks the froth collected in the eddies, that I must attrib- 

 ute the effect to a similar action either of the currents of the 

 air or sea. Under this supposition we must believe that the 

 various organized bodies are produced in certain favourable 

 places, and are thence removed by the set of either wind 

 or water. I confess, however, there is a very great difficulty 

 in imagining any one spot to be the birthplace of the millions 

 of millions of animalcula and confervae: for whence come 

 the germs at such points? the parent bodies having been 

 distributed by the winds and waves over the immense ocean. 

 But on no other hypothesis can I understand their linear 

 grouping. I may add that Scoresby remarks that green 

 water abounding with pelagic animals is invariably found 

 in a certain part of the Arctic Sea. 



