INTRODUCTION TO CEYPTOGAMIC BOTANY. 103 



mange ; but they are now largely employed, even in the central 

 parts of England, for feeding pigs, in the form of a jelly mixed 

 up with meal and other ingredients. They contain a consider- 

 able quantity of gummy and amylaceous matter, and, possibly, 

 some albumen, to which they owe what medicinal property 

 they possess, for they do not appear to contain iodine. Ac- 

 cording to Schmidt, the jelly of carrageen is identical as 

 to its chemical formula with starch and sugar, C " H "* 

 O '°. Pereira considers it a distinct body from gum, starch, 

 and pectin. Nearly the same substance exists in the Ceylon 

 Moss, and, probably in many allied Alga3, as in the Corsican 

 Moss, Plocaria Helminthochorton, which contains besides a 

 minute quantity of iodine, and has, perhaps, no active 

 qualities. A more delicate jelly is prepared from Oracilaria 

 lichenoides, spinosa, and Gigartina speciosa; the use of which 

 is, however, confined, almost exclusively, to the East or 

 Australia. It is a mistake to suppose that the Chinese 

 swallows' nests belong to the same category, since the sub- 

 stance of which they are formed is secreted by the birds them- 

 selves. Oracilaria tenax, together with some other species, 

 however, affords another more important substance, viz., a 

 glue, cement, or varnish, which is extensively used in China. 

 Durvilloea utilis is employed to thicken soup ha Chili. 

 One of the best edible preparations from Algffi is the 

 laver, which is, however, more used in the western than the 

 eastern parts of England. Few condiments are more esteemed 

 than this, where the taste has become habituated to its use ; 

 but, like olives, it is seldom approved at first. It is, no doubt, 

 a very wholesome food, but its use is not likely to become 

 more widely diffused than it is at present. A species of Nostoc 

 is largely consumed in China as an ingredient in soup ; and 

 an allied Alga has been found a welcome article of food in 

 the Arctic regions. The cattle in Scotland and Norway browse 

 upon the seaweeds at low water ; and the succulent branches 

 and fronds of the Gaulerpce are the favourite food of turtles. 

 The whole tribe affords nutriment for hosts of mollusca and 

 fishes. Several minor uses are made of Alga3, such as the manu- 

 facture of handles for tools from the thick stem of Lessonia 

 fuscescens, and some other species, and of fishing lines from 



