97 



were oi-igiiicallj fillings of llie vessels. Only few of tiie samples were 

 flattened (± J or 2 mm. thick); they seem to have been fillings of 

 the clefts in the wood, evolved from the expansion conseqnent on 

 the growth of the stems. On the fractnres all the fragments are snow- 

 white, somewhat ci-etaceons, bnt slightly harder (H =: 2) '). The 

 specific weight is 2.240. 



In thin sections two different snbstances are discernible nnder the 

 microscope. The one presents itself as irregnlar grains, clear as 

 water, often enclosing the rest of the forest material i.e. libriform 

 fibres. They are yellowish-brown, elongated, isolated cells, more or 

 less cnrved and pointed at the extremities. The secretion from the 

 wood very likely cansed parts of the wood-lissne to be dislocated 

 and the fibres to be deformed. The exponent of refraction is not 

 very high and as to double refraction in polarised light, the inter- 

 ference colours do not rise higher than the blue of the second oider. 

 The angles of extinction were 21 — 22 1 degrees, but some were 31° 

 or even 37°"). A proper orientation could rarely be obtained owing 

 to the lack of crystals and of distinct cleavage planes. 



The second snbstance is turbid and finely fibrous. It consists of 

 spherolithlike aggregate, presenting in polarised light a slanting cross, 

 which shows that, like the first, it belongs to a clinobasic system 



of crystals. The very fine need- 

 les generally have a length 

 of 0.05 mm., thongh (here are 

 some of still smaller dimen- 

 sions. Howevei' the fibres some- 

 times exiend into prisms 0.2 

 mm. long and 0.008 mm. broad. 

 The lefVaction is stronger with 

 them than with the grains 

 described above, but like them 

 they are optically positive. It 

 seems to me that the phos- 

 phate appearing in the form 

 of aggregates is of secondary 



de in hel boschdistrikt Madioen voorkomende zoogen. djativariëteiten. Boschbouw- 

 kundig Tijdschrift. Tectona 4, Noonhvijk-Weltevreden l'.^ll, p. 473). 



') J. VV. H. CoRDES (De Djatibosschen op Java, Batavia 1881, p. 27) says on 

 the contrary that the concretions are as a rule very hard, so that they sometimes 

 injure the axes. 



-) In the process of grinding thin sections some pressure on the soft grains may 

 have been of some influence on the optic qualities. 



