726 SYSTEMATIC BOTANY. 



Iodine is, however, still prepared from kelp. Some Algse have 

 been reputed to possess vermifugal properties ; none are known 

 to be poisonous. 



Several Algae are remarkable for imparting colours to water, 

 snow, &c. Thus, Protococcus (Palmella) atkmtmis gives a red 

 colour to certain parts of the Atlantic ; P. nivalis contributes 

 to communicate a red colour to snow ; and P. viridis, a green 

 tint ; Dolichos^pernum Thompsoni imparts a green colour to the 

 Serpentine and to some Irish and Scotch lakes ; the red colour 

 of the Ked Sea is also in part attributed to the presence of 

 Trichodesmium erythroiuin ; &c. &c. Dr. Eobert Brown, of 

 Edinburgh, has also shown that the discoloration of the Arctic 

 Sea is due to Diatomucete, but principally to Melosia arctica, and 

 that these form the brown-staining matter of the "rotten ice" 

 of northern navigators. 



Some Algge are met with in diseased animal tissues. The 

 Achlya frolifera, which attacks the gills of gold fishes, &c., and 

 Sarcimda ventriculi, found in the stomach, &c. of animals, may 

 be enumerated as amongst the most remarkable of such forms. 



Alaria esculenta (Bladderlock^;, Hen-Ware, or Honey- Ware) contains man- 

 nite. It is employed for food in Ireland, Scotland, Iceland, and other 

 northern regions of the world. Berkley says that " it is the best of all the 

 escnlent Algse when eaten raw." 



Chondi-us. — C. crispus is the source of our officinal Carrageen or Irish Moss. 

 It possesses nutiitive, emollient, and demulcent properties, and may be em- 

 ployed in the form of a decoction, jelly, &c., in puhnonary complaints, &c. 

 Bandoline or fixature, used for stiffening the hair, &c., is generally pre- 

 pared from Carrageen. C. mamillosus or Oigaitina mamillosa is always 

 found in the Can-ageen Moss of the shops. Its properties are similar. Car- 

 rageen Moss is sometimes employed as a siibstitute for size. 



Durvilloea utilis is used for food by the poorer inhabitants on the western 

 coast of South America. 



Fucus. — Several species contain mannite, as F. vesiculosus, F. nodosus, and 

 F. serratiis. These species were formerly largely used in the preparation of 

 kelp, and are now collected on om- shores for manure. F, veskulosua. 

 Sea Wrack. — This Alga is much used in winter in certain islands of Scotland 

 for feeding horses and cattle. The expressed juice of its vesicles or bladders 

 has been given internally, and frictions of the plant have been employed 

 externally, in glandular and scrofulous affections. A kind of wine prepared 

 from this Alga has also been used with success in similar diseases. The sub- 

 stance called Vegetable Ethiops, which has been likewise employed in &uch 

 cases as the above, is a kind of charcoal produced by the incineration of this 

 Alga in close vessels. The beneficial effects in these instances are principally 

 due to the presence of a small quantity of iodine. 



Gelidium corneum, as already noticed, is nutritive. It is the Algue de Java, 

 from which M. Payen first obtained Gelose. It forms a favourite article of 

 food in Japan, Sac, and is also used in the manufacture of a kind of 

 glue, &c. 



Gigaiiina speciosa (Eucheuma speciosum) is the jelly plant of Australia. 

 It is employed for food and for maldng size, cement, Sac. (See Chondrus 

 and Graeilaria.) 



Gracilaria {Plocaria).—G. lichenoides (Plocaria Candida) and G.confervoides 

 are the sources of Ceylon Moss. This is nutritive, emollient, and demulcent, 

 and may be employed in the form of a decoction or jelly, as a food for 

 children and invalids, and medicinally, in pulmonary complaints, diarrhoea, 

 Sic It is sometimes imported under the name of Agar-agar, but Gigartina 

 apinosa has been also imported under the same name. Both species are 



