EESIN OF THE OUTER BARK OF MELALEUCA UNCINATA. 233 



The thin paper-like bark, or epidermis, entirely clothes 

 the stems, and branchlets, and when dry peels off in thin 

 semi-transparent sheets, without distinctive structure. 

 The under bark is quite separate, splits longitudinally, and 

 does not contain the resin to any extent. This inner bark 

 gives a fair quantity of ash on ignition, and isolated crystals 

 of oxalate of lime can be detected microscopically in the 

 section. 



When ignited at one end, a piece of the thin outer bark 

 continues to burn like a candle until wholly consumed, 

 giving a bright flame with a considerable amount of black 

 smoke, and an odour of burning resin. It is evident how 

 greatly this material would aid fires in the Australian bush 

 where this Melaleuca grows. 



The inflammable substance in this bark consists almost 

 entirely of a resin, and only a small proportion of a vege- 

 table wax was detected. 



The presence of a resin in quantity is a most unusual 

 occurrence in plants belonging to the natural order Myr- 

 tacese, and I have been unable to find but one previous 

 instance of a true resin having been recorded for this genus; 

 (Hartzer, Ber. 9, 314, in the leaves of Eucalyptus globulus). 



Solereder refers to a statement by Moller (Rindenan- 

 atomie, pp. 344-347) that resin spaces occur in the 

 secondary bast in Eucalyptus viminalis and E. Stuartiana 

 as an improbable one, and that it required re-examination. 



The outer bark of M. uncinata is reddish-brown extern- 

 ally with grey patches at places; the markings indicate a 

 more or less concentric arrangement, and the bark can be 

 peeled off in that way. The outer bark when removed from 

 a stem 1 cm. diameter was only f mm. thick, was semi- 

 opaque, reddish-brown internally, and somewhat tough; 

 the thickest bark in the bulk sample received was under 

 1 mm. After boiling in alcohol to remove the resin, the 



