358 



ERNEST WAIJREN. 



The Weenenwood is the lightest, and we have already seen 

 that it is soft (2—3 of scale) and friable. It might, therefore, 

 have been anticipated that a considerable amount of space is 

 unoccupied by solid matter, and it is seen by the above table 

 that some 25 per cent, is thus vacant. The greater the amount 

 of such space the greater the play there would be for contor- 

 tion and compression under pressure subsequent to fossiliza- 

 tion, and as a matter of fact some of the most shattered 

 samples possess the most vacant space (PI. XXA", fig. 3). 



V. FOSSILIZATION. 



Considerable differences occur in the maimer of fossilization. 

 In silicitication the first process seems to be the infiltration of 

 silica in solution into the actual substance of the walls of the 



Text-fig. 2. 



Examples of contortion in specimens of fossil wood of Dadoxylon (A, 



B, C) and Eugenia (D). 



A. — X 2. Transverse section of Dadoxylon sp.. Dannhauser. Natal, 

 Mns. No. 160. showing black compression Ijands arising from simple 

 downward pressure. The course of three medullary rays is espe- 

 cially indicated. 



B. — X 3. Transverse section of Dadoxylon (probably D. australe), 

 Tongaat, Natal, Mns. No. 217, showing eflJects of pressure exerted 

 in at least two directions. 



C. — X 20. Transverse section of Dadoxylon (probably D. australe), 

 Mns. No. 169, showing the eifects of pressure exerted from various 

 directions. 



D. — X 4. Transverse section of Eugenia, Port Dnrnford. Mus. No. 

 232, showing the remarkable contortion of the tissue with little 

 actual rupture of the elements. 



