16 



CONFERVACEiE. 



[Algals. 



Confervas ai-e more frequently found in the temperate parts of ^1?^^ J^J^^^^ ^^^^ 

 within the troi)ics,occupvinff both salt and fresh water, but more espee ally the lattei, 

 :T:^T!^:s\ii common to both. One of them, the T.res^ er^^etorm. 

 grows on the W"h1, but in places that are very damp ^'^^ often mj^dated 

 others among the oscillating species cover the humid surface of rocks or earrti, 

 and the interstices in the pavement of cities ; some eyen grow u. hot ^V^'-^f^^l^^^J 

 high temperature. Ulva thermalis lives in the hot ^-^^^^:^:,:r^Z: 



kester speaks of Oscillatorias 

 found in the sulphm-etted hy- 

 drogen water of Harrowgate 

 (Ann. N. H. \\\. 107); and 

 Calothrix nivea is said to have 

 occuiTed there also. They 

 often give a peculiar colom' 

 to large bodies of water. The 

 Red Sea has derived its name 

 from the abundance of Tricho- 

 desmium erytlrrseum 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 Haamatococcus sali- 

 nus, two of the most simple of 

 this order*. Hsematococcus Nol- 

 tii stains crimson the marshes 

 of Sleswick. 



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

 for its pecuHar greenness, owes its colour to the presence of his Oscillatoria aeruges- 

 cens. (Ann. N. H.\.\.) The green of the Grand-canal docks near Dublin has been 

 found to arise from the presence of a Sphajrozyga (Trichormus.4Wm.) and ui hke manner 

 Mr. Thompson found that the water of Ballydraui lake is coloured 

 Sphterozyga ( Anabaina) spu-aUs, and that in the same 

 place broad verdigris patches proceed from collections 

 of Aphanizomenon incurvum. {Ann. N. Hist. v. 83.) 

 It has 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 wooUen 

 fabric, whence it has gained the name of water- 

 flannel. Confervre sometimes attack diseased animal 

 tissue. Mr. Goodsir has described such an instance 

 in the case of a gold-fish. {Ann. Nat. Hist. ix. .S36.) 

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

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



Fig.. V, 



Fig. VI. 



* " On the 8th July 1843, I entered the Red Sea by the straits of Babelmandel, onboard the Atalanta 

 steamer. On the 15th the burning sun of Arabia suddenly awoke me with its brilliancy unannounced by 

 tlie dawn. I was leaning mechanically out of the poop windows, to catch a little of the fresh air of night 

 before the sun had devoured it, when, imagine my surprise to find the sea stained red as far as the ej-e 



could reach behind the vessel. If I was to attempt to describe this phenomenon, I would say that the 



surface of the ocean was entirely covered with a close thin layer of fine matter, the colour of brickdust, 

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

 bottle, it became in the course of a day deep violet, while the water itself had become a beautiful rose 

 colour. This appearance extended from Cosseir, off which we were at daybreak on the 15th May, to Tor, a 

 little Arabian village, which we made about noon the next day, when it disappeared, and the sea became 

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

 rendus, xix.171. — Similar appearances have been mentioned by Mr. Darwin ; and Mr. Hinds, when at 

 anchor off Libertad in the Pacific, and at the Abrolhos, i)erceived large quantities of another species of 

 Trichodesmium, which e.xhaled a most disagreeable smell. To this cause, or one of tlie same kind, is pro- 

 bably referable the phenomenon mentioned in the Colombo Herald of May 14, 1844 : " The sea to the 

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



Fig. V. — 1. Hydrodictyon utriculatum ; 2. portion of full-grown plant ; 3. portion of a joint in which 

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

 Fig. VI.— Sphaerozyga spiralis. 



