96 



DOMESTIC BOTANY. 



Agar Agar, or Agal Agal. It is largely collected and made 

 into a jelly much resembling that obtained from calves' feet, 

 and forms an extensive article of trade at Singapore and 

 Borneo, constituting part of the cargo of the Chinese 

 junks on their return voyages. It is also used as a varnish, 

 more especially for the paper employed in the manu- 

 facture of Chinese lanterns, to which it imparts a yellow 

 tinge. 



Plocaria tenax. Native of the Indian and Chinese seas. 

 It contains much gelatine, and is considered to be the chief 

 substance of which the sea-swallows compose their nests. 

 The process imparts to them a peculiar character, and they 

 form an important article of commerce among the Chinese, 

 by whom they are considered a great luxury. 



The Seaweed Family. 



(FUCACE^.) 



Plants inhabiting the sea, or growing in fresh water. In 

 general they consist of thick, firm, leathery fronds of a brown, 

 olive, green, or red colour, narrow or broad, entire or vari- 

 ously divided, their stems being solid or hollow, often of a 

 considerable thickness, some slender and of a great length ; 

 when dried oft-en becoming hard and horny. In some species 

 their reproductive spores are borne in bladder-like cases. 

 This extensive family forms the forests and shrubberies of 

 the ocean. About 450 species are enumerated, abounding in 

 all seas, even to high latitudes. 



Wrack. During storms the force of the waves uproots 

 large quantities of seaweeds of different species, which are 

 wafted on shore and left by the receding tide. They are 

 chiefly such strong- growing species as Fucus vesiculosus^ 

 F. nodosus, F. senatus, Laminaria digitata, and L. hulhosa 

 (known also as tangle). In former years the collecting, dry- 

 ing, and burning of " wrack" furnished employment to large 

 numbers of people in Scotland and Ireland. The ashes con- 

 tain an alkali caUed " kelp," used in the manufacture of soap 



