52 



HARDWICKE'S SCIENCE-GOSSIP. 



THE COLOUR OF THE RED SEA. 

 By Dr. Stonham. 



OX a recent voyage to the East, our route lay 

 through the Red Sea, the water of which is 

 usually of a bright sky-blue colour ; but sometimes 

 we came to long streaks of a red-brown colour, often 

 two or three miles long, but of no great breadth — not 

 more than two or three hundred yards. These streaks 

 presented an irregular but well-defined border, so 

 tliat a glance was sufficient to show the exact line 

 v. here the red left off, and the ordinary blue began. 

 This same appearance was also observable in the 

 Gulf of Aden. I only saw it in calm weather, but 

 it is rare that the water is very rough in the Red 

 Sea, and I am unable to say whether it is to be seen 

 in rough weather or not. 



The favourite theory with the sailors concerning 

 this colouring was, that it was due to spawn, but of 

 what fish they did not seem very certain; others 

 again thought that animalcula caused it. 



matter of a pale yellow colour had taken its place. 

 Some of the cylindrical bodies could be observed in 

 process of undergoing the change ; the segments at 

 one end would be visible, while, at the other, they 

 were indistinct and filled with granular material. 



The red appearance of the sea was due to the 

 bodies breaking up into this granular material ; 

 previous to this they gave no colour observable 

 more than a few yards off, and for that distance only 

 a slight light brown appearance mixed with the blue. 



I find that Darwin in his " Voyageof a Naturalist," 

 mentions that he came across red bands of this kind 

 near the Abrohlos Islets off the coast of South 

 America, and says that they are due to Conferva? 

 of the species Trichodesmium cryt/inaii/i, and that 

 they are also found in the sea near x\ustralia. It 

 appears, therefore, that they are by no means peculiar 



Fig. 45. — Confervas in bundles. X 40. 



On drawing up some of the water in a bucket, I 

 found a reddish scum floating on the top, but mixed 

 with this, and also distributed through the body of the 

 water, numberless little objects just visible to the 

 naked eye, and looking like little pieces of cotton 

 finely cut up. These were colourless, if seen singly, 

 but, seen in the mass, gave a light brown colour. The 

 colour to the sea was given almost entirely by the 

 reddish scum. After some of the water had been 

 kept standing for twenty-four hours, nearly all these 

 little bodies had disappeared, but the scum was 

 greatly increased in quantity, being, in fact, formed 

 by the degeneration and breaking up of these. 



Under the microscope, they were found to consist 

 of bundles of long, jointed, cylindrical bodies, quite 

 colourless, and made up of from fifteen to twenty 

 segments, each segment being nearly square and 

 apparently structureless. The last segment differed 

 from the others in shape forming a hook. Thirty to 

 forty of these cylindrical bodies were aggregated to 

 form each bundle, and it was rare to find one detached 

 from the bundle. The hooked ends were not arranged 

 all at one end in the bundle, but some at one end, 

 some at the other. On examining some of the water, 

 that had been kept, I found the bundles very indistinct, 

 the structural character was obliterated and a granular 



? 



3 



':>/«i $"//# 



A 



1/ 



Fig. 46. — Single confervae, 

 when separated from a 

 bundle. X 100. 



mm 



Fig. 47. — Confervae bundle 

 breaking down into gra- 

 nular material. 



to the Red Sea, and can bear a lower temperature 

 than they experience in those hot waters. Their 

 distribution in the water in bands of great length 

 and little breadth, their well-defined margins, and 

 how and when they take their origin, are facts which 

 I cannot explain, and concerning which I shall be 

 glad to gain information. 



THE VALE OF LLANGOLLEN: 

 A PERSONAL VISIT. 



HAVING read with great interest the glowing 

 paper written by the Editor of Science- 

 Gossip in last July number, of his visit to Llangollen, 

 my sister and I determined to visit it ourselves. We 

 owe Dr. Taylor thanks for our stay at one of the 

 sweetest spots we ever stayed at. Armed with the 

 number of SciENCE-Gossil 1 containing his paper, we 

 went to Llangollen in the middle of September, and 

 visited nearly every locality he names for fossils, and 

 our searches were crowned with success. Hafod is a 

 wonderful spot. We believe we saw there some of 

 the identical huge corals which Dr. Taylor describes as 

 being beyond his strength to remove, and there they 

 still remain for other admiring eyes to rest upon. My 



