558 ALG.E. 



gassum bacciferum, the Gulf-weed, is found floating in great quan- 

 tities on each side of the equator in the Atlantic, Pacific, and Indian 

 oceans. Protococcus nivalis and viridis are said to occur in red and 

 green snow. The red and green colours of certain lakes and seas 

 are attributed to species of Trichodesmium and Sphcerozyga. Ac- 

 cording to Dr. Joseph Hooker, Diatomacece are found in countless 

 numbers between the parallels of 60 and 80 S., where they give 

 a colour to the sea, and also to the icebergs floating on it. The 

 death of these bodies in the South Arctic ocean is producing a sub- 

 marine deposit, consisting entirely of the siliceous particles which 

 entered into the composition of these plants. Conferva crispa, called 

 Water-flannel, forms beds of entangled filaments on the surface of 

 water. Species of Tyndaridea also occur in thick green patches. Hy- 

 drodictyon utriculatum. Water-net, has the appearance of a green net, 

 composed of filaments which enclose pentagonal and hexagonal spaces. 

 Acklya prolifera, and other Confervse, are developed occasionally on 

 living animals, such as on the gills of the gold-fish and of trout. Cer- 

 tain organisms have been detected in the human stomach, which appear 

 to belong to this order. One of these is called Sarcinula ventriculi by 

 Goodsir, and was ejected by" vomiting in a case of pyrosis. It consists 

 of square cells united together in sets of four, and propagating by 

 division. 



1130. The plants of this order supply a quantity of gelatinous mat- 

 ter, and many of them are used for food. Kelp is obtained by the 

 burning of Sea- weeds, and iodine is procured from them. Sphcerococ- 

 cus (Chondrus) crispus, Carrageen or Irish Moss, supplies a nutritious 

 article of diet. Khodymenia palmata, Dulse, Alaria esculenta, Iridcea 

 edulis, young plants of Laminaria digitata and saccharina, Tangle, as 

 well as various species of Porphyra, Laver, and Ulva, Green Laver, 

 are esculent. The edible swallows'-nests of the East are said to be 

 formed of a species of Galidium. Sphcerococcus cartilaginous, var. seta- 

 ceus, is used in China as a substitute for these nests. Agar-agar is a 

 sea- weed of a similar kind. Nostoc edule is used in China as an article 

 of food. The use of burnt sea- weed, in cases of scrofulous swellings, 

 has been superseded by the discovery of iodine, the active ingredient. 

 Plocana (Gigartind) Helminihocorton, under the name of Corsican 

 Moss, was formely used as a vermifuge. The Charas have frequently 

 a peculiarly fetid odour, and their presence is said to give rise to 

 malaria. Occasionally they communicate their odour to the water of 

 reservoirs, and render it unpleasant. It is of importance for Water 

 Companies to see that Charas do not exist in the streams which supply 

 the water for their reservoirs. 



For full details on the subject of Classification, the arrangement and char- 

 acters of natural orders, and the properties of plants, the student should con- 

 sult Lindley's Vegetable Kingdom. 



