SANDARAC 471 



acid (10 per cent.), and sandaracoresene. Callitrolic acid is easily 

 converted into the lactone which is insoluble in alcohol. 



Uses. Sandarac is chiefly used in the manufacture of varnishes ; 

 it is paler in colour than shellac, and is therefore more suitable for 

 light woods. 



Varieties. Australian sandarac, from C. verrucosa, Robert Brown, 

 is occasionally imported. The tears are softer, larger, and more 

 aromatic than those of African sandarac, which it otherwise resembles. 

 Its composition is similar, but it contains more volatile oil and more 

 inactive pimaric acid. 



SHELLAC 



(Lac, Lacca) 



Source, &C. Shellac is a resinous exudation that encrusts the 

 bodies of Coccus (Tachardia) Lacca, Kerr (Order Hemiptera, Family 

 Coccidce). 



These minute insects live upon plant juices sucked up by a 

 proboscis that penetrates the succulent tissues of the host. Twice 

 or sometimes three times in the year the larvse emerge from the dead 

 bodies of the females, crawl away and establish themselves in new 

 situations. They are minute creatures, about 0-5 mm. long, of an 

 orange-red colour with fully formed feelers and powerful legs, but no 

 visible separation of the body into head, thorax, or abdomen. They 

 puncture the young twigs with their probosces and suck up the 

 juices ; they become fixed, and their legs, being no longer required, 

 drop off ; a resinous secretion forms around their bodies and gradually 

 more or less encrusts the twigs. At the period of maturity the males, 

 which undergo a complete metamorphosis, escape from their pupae, 

 impregnate the females and shortly afterwards die. The females 

 rapidly increase in size, assume a bright red colour, develop viviparous 

 larvse and die. New colonies are established by cutting off twigs with 

 the gravid females and tying them on to various trees. 



The principal trees visited by the lac insects are Aleurltes laccifera, 

 Willdenow (N.O. Euphorbiacece) , Ficus religiosa, Linne (N.O. 

 Urticacece), Schleichera trijuga, Willdenow (N.O. Sapindacece) , Butea 

 frondosa, Roxburgh (N.O. Leguminosce) . Acacia arabica, Willdenow 

 (N.O. Leguminosce), and Cajanus indica, Sprengel (N.O. Leguminosce), 

 are cultivated for that purpose. 



Whether the resin is secreted by the insects or produced by the 

 plant as a result of the irritation caused by the insects is at present 

 not definitely known. The resin shows, in its chemical composition, 

 a variation from vegetable resins, and this seems to indicate that it 

 owes its origin, in part at least, to a change effected by the insects in 

 the constituents of the plant. 



