382 EAMBLES OF A NATUEALIST. [Ch. XXII. 



instead of a uniform pellicle, the dust would be arranged 

 in long irregular parallel lines, or bands, extending un- 

 broken as far as the eye could reach, and taking the 

 direction of the wind. On one occasion we crossed a 

 single band of this character, the only one seen on that 

 day. 



The frequency of this appearance in the Cliina Sea may 

 be judged of by the fact that out of four times that I crossed 

 that sea, I observed the sea-dust to be more or less abim- 

 dant during three of them, and assuming one or other of 

 the appearances described. The fourth time was in winter 

 (December), and during the height of the monsoon, the 

 wind being very' boisterous and the sea very rough, so that 

 this substance was doubtless so thoroughly washed and dis- 

 persed by the waves as to be indistinguishable amid the 

 turmoil and foam. The most northerly point at which I 

 observed the accumulation of Trichodesmium forming a 

 pellicle upon the surface, was at the north entrance of 

 Formosa Channel, in lat. 25^° ; and it is somewhat remark- 

 able that I should have seen none south of the Equator in 

 the Indian Ocean, Ehio Strait being the most southern 

 locality. On one occasion indeed, in lat. 28j° S., it mani- 

 fested its presence by the same indications by which I first 

 noticed it, namely a scintillating of the scattered sheaves 

 below the surface — a fact which I proved by examining the 

 water; and in the Atlantic, in lat. 80° S., the same appear- 

 ance was closely followed by two or three bands or streaks, 

 in which it was quite dense, discoloring the water. 



But it is worthy of notice that on all these occasions the 

 colour of the Trichodesmium was the same, viz. a yellowish 

 brown, and never at any time red, or approaching it — much 

 less the rouge de sang of the French botanists. On only 



