16 



CONFERVACE^E. 



L Alga us. 



Confervas arc more frequently found in the temperate parts of the world than 

 within the tropica, occupying both salt and fresh water, but more especially the latter, 

 and several species are common to both. One of them, the Tiresias ericetorurn, 

 groWB mi the gr0UR-l, lmt in places that are very damp, and often inundated ; 

 others among the oscillating Bpeciea cover the humid surface of rocks or earth, 

 an. I the interstices in the pavement of cities; some even grow in hot springs of a very 

 high temperature. 1'lva tliermalis lives in the hot springs of Gastein, in a temperature 



of about 117° Fahr. Dr. Lan- 

 kester speaks of Oscillatorias 

 found in the sulphuretted hy- 

 drogen water of Harrowgate 

 (Aim. N. If. vii. 107); and 

 Calothrix nivea is said to have 

 occurred there also. They 

 often give a peculiar colour 

 to large bodies of water. The 

 Red Sea has derived its namo 

 from the abundance of Tricho- 

 desmium erythraeum which 

 floats in it, and concerning 

 which MM. Evernor Dupont 

 and Montague have given a 

 curious account.* Dunal states 

 that the crimson colour of the 

 salt-water tanks on the coast 

 of the Mediterranean is owing 

 to the presence of Protococcus 

 salinus and HEematococcus Sali- 

 nas, two of the most simple of 

 this order. Hoematococcus Nol- 

 tii stains crimson the marshes 

 F 'S' v - of Sleswick. 



Dr. Drummond ascertained that the Irish lake of Glaslough, which is remarkable 

 lor its peculiar greenness, owes its colour to the presence of his Oscillatoria seruges- 

 ci-ns. (Ann. X. //. i. 1.) The green of the Grand-canal docks near Dublin has been 

 found to arise from the presence of a Sphterozyga (Trichormus A Urn.) and hi like manner 

 Mr. Thompson found that the water of Ballydrain lake is coloured green by 

 Spheerozyga < Anabaina) spiralis, and that in the same 

 place broad verdigris patches proceed from collections 

 of Aphanizomenon incurvum. (Ana. N. Hint. v. 83.) 

 It lias also occurred that acres of inundated meadow 

 land have been clothed to the depth of an inch with 

 a thick entangled layer of Conferva crispa, which 

 then forms a texture not unlike that of some woollen 

 fabric, whence it lias gained the name of water- 

 Ratine!, t lonfervaa sometimes attack diseased animal 

 tissue. Mr. (ioodsir has described such an instance 

 in the case of a gold-fish. (Ann. Nat. UlM.'w. 336.) 

 It has been ascertained that this is of very common occurrence, and that the plant 

 which makes the attack is the Achlya prolifera. This production has been carefully 



co 





C 



n 



Fig. VI. 



* " on the Bth July lxt.'f, I entered the Red Sea by the straitsof Babelmandel, onboard the Atalanta 

 steamer. On the 16th Hie burning iun <>f Arabia suddenly awoke me with its brilliancy unannounced by 

 the dawn, i was leanin | mechanically out of the poop windows, to catcha little of the fresh air of night 

 before the sun had devoured it, when. Imagine my surprise to rind the sea stained red as far as the eye 



could reach behind the vssd. If 1 was to attempt to describe this phenomenon, I would Bay that the 



■'"'■' I the ocean was entirely covered with a close thin layer of tine matter, the colour of brickdust, 



but lightly orange Mahogany sawdust would produce such an appearance. — When put into a white glass 



mi. . .i became In the course of B day deep violet, while the water itself had become a beautiful rose 

 colour, I hlsappaaranos extended mud Cosseir, off which we were at daybreak on the 15th May to Tor a 



tittle Arabian village, which we made about noon the next dav, when it disappeared and thVs'ea became 

 blue as before. During this time wfi must have passed through about 256 miles of the red plant " Comptei 

 . \i\ 1 T I . — Similar appearances have been mentioned bv Mr. Darwin- and Mr Hinds when at 

 anchor M Libertad In the Pacific, and at the abrolhos, perceived large quantities of another species of 

 I rlehodi smlum, which exhaled a most disagreeable smell. To this cause, or one of the same kind, is pro- 

 bably referable the phenomenon mentioned in the Colombo Herald of May 14 1X44 • "The sea to the 

 southward of Colombo, and, more lately, opposite the fort itself, has presented a very uncommon appear- 



I V -1 llydrodic.tyonutriculatu.il; 2. portion of full-grown plant; 3. portion of a joint in which 



nules have commenced to dispose themselves in pentagons, the rudiments of the new plant. 

 FUr, V IV— Bphserosjga spiralis. y 



