1832.1 DISCOLOURED SEA. 17 



rants, and immense herds of great unwieldy seals derive, on some 

 parts of the coast, their chief sustenance from these swimming 

 crabs. Seamen invariably attribute the discoloration of the 

 water to spawn ; but I found this to be the case only on one 

 occasion. At the distance of several leagues from the Archipe- 

 lago of the Galapagos, the ship sailed through three strips of 

 a dark yellowish, or mud-like water ; these strips were some 

 miles long, but only a few yards wide, and they were separated 

 from the surrounding Mater by a sinuous yet distinct margin. 

 The colour was caused by little gelatinous balls, about the fifth 

 of an inch in diameter, in which numerous minute spherical 

 ovules were embedded : thev were of two distinct kinds, one being- 

 of a reddish colour and of a different shape from the other. I 

 cannot form a conjecture as to what two kinds of animals these 

 belonged. Captain Colnett remarks, that this appearance is 

 very common among the Galapagos Islands, and that the direc- 

 tion of the bands indicates that of the currents ; in the described 

 case, however, the line was caused by the wind. The only other 

 appearance which I have to notice, is a thin oily coat on the 

 water which displays iridescent colours. I saw a considerable 

 tract of the ocean thus covered on the coast of Brazil ; the sea- 

 men attributed it to the putrefying carcass of some whale, which 

 probably was floating at no great distance. I do not here men- 

 tion the minute gelatinous particles, hereafter to be 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 Mere as coinstantaneous as in 

 a regiment of soldiers ; but this cannot happen from any thing 

 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 re- 

 sembles that which may be seen in every torrent, M'here the stream 

 uncoils into long streaks the froth collected in the eddies, that 

 I must attribute the effect to a similar action either of the cur- 

 rents of the air or sea. Under this supposition we must believe 

 that the various organized bodies are produced in certain favour- 



c 



