150 FAMILIAR TREES 



Viper and all other venemous Serpents, except the 

 Aspe." 



The ash, hoth of the stem and leaves, contains an 

 abundance of sodium sulphate ; and it is probably 

 to the presence of this salt that the plant owes its 

 diuretic properties, which were recognised by Galen 

 and Dioscorides, and by the early Arabian medical 

 writers. A decoction of the young twigs is said to be 

 used by the Tartars for rheumatism and for braises, 

 and the plant has been used in Denmark as a 

 substitute for hops. Two species are employed as 

 astringents in Indian medicine; but galls produced 

 on them by insect puncture are more powerful than 

 the plants themselves. A Syrian species, closely alhed 

 to T. gallica, when punctured by an insect. Coccus 

 manniparus, exudes a mucilaginous sugar which the 

 Arabs term "manna." Burckhardt thus describes 

 the secretion of this plant, which grows abundantly 

 in a valley north of Mount Serbal: — 



" In the month of June it drops from the branches upon the 

 fallen twigs and leayes, which always cover the ground beneath the 

 tree in its natural state. The manna is collected before sunrise, 

 when it is coagulated ; but it dissolves as soon as the sun shines on 

 it. The Arabs clear away the leaves and dirt which adhere to it, 

 boil it, strain it through a coarse piece of cloth, and put it into 

 leathern skins. In this way they preserve it till the following year, 

 and use it as they do honey, to pour over their unleavened bread, or 

 to dip their bread into. I could not learn that they ever made it 

 into cakes or loaves. The manna is found only in years when copious 

 rains have fallen ; sometimes it is not produced at aU. It never 

 acquires that degree of hardness which will allow of its being 

 pounded, as the Israelites are said to have done with the manna with 

 which they were miraculously supplied ; nor does it possess the same 

 nutritive properties. Some travellers suppose this substance to be 

 the produce of an insect which Infests the Tamarisk. The quantity 



