THE AUSTRALIAN GREY MANGROVE. 275 



"Bark used for tanning," — Birdwood, (Products of India,, p. 

 361,— Watt). 



"Bark used in Rio de Janeiro for tanning," — (Surgeon H. W. 

 Hill). 



"Bark astringent," (Surgeon Major W. Dymock, Bombay). 



A noticeable feature about this tree is that it is impos- 

 sible to kill it by ring-barking, for trees are to be seen in 

 the Port Macquarie district that have not suffered in the 

 least by such treatment, but are in just as flourishing a 

 condition as if they had never been touched by the axe- 

 man. This tree then is an exception to the rule. The fact 

 that this mangrove should live on in spite of this general 

 method of killing trees is, in my opinion, due to each 

 "ring" being in itself a fascicular bundle, consisting of the 

 elements or factors that go to make up such a combination 

 of phloem, xylem, etc. Cutting away then what is regarded 

 as the bark is really only depriving the tree of a ring of 

 an outer cortex, and further the remaining numerous 

 phloem streaks in the individual rings are quite able to 

 carry on the function of that injured on the outside, and 

 so the tree lives, — a character unique as far as my know- 

 ledge goes in the botanical world. 



10. Concentric Rings and their relation to the age of the tree. 

 When carrying out an investigation on the fibres of 

 Australian trees, I was particularly attracted by the 

 peculiar disposition of those of this tree, they being quite 

 unlike anything I had previously met with. 



Mr. T. Dick of Port Macquarie, N.S.W., who was much 

 interested in the subject of the manufacture of shields from 

 this tree by the aborigines, also drew my attention to the 

 fact that it was most difficult to split this mangrove timber 

 radially. It was these features which caused me to make 

 an investigation of the histology of the timber (supra). 



