56 TIMBER AND SOME OF ITS DISEASES. [CHAP. 



All have a dense red, brown, purple, or 

 black heart (75 to 85 Ibs. the cubic foot) : 

 ' e.g. Mesua ferrea, Heritiera littoralis, 

 Xylia dolabriformis, Hardivickia 

 binata, Terminalia tomentosa, Dyos- 

 pyros Melanoxylon, &c. These a^e 

 the chief hard woods of India, 

 y The following (and others) are less easily 

 classified, and other characters have to be 

 used in grouping them : 



e.g. Dalbergia Sissoo, D. latifolia, Bassia 

 latifolia, Melia indica, Acacia 

 arabica, A. catechu, Lagerstroemia 

 parviftora, Pterocarpus Marsupium, 

 &c. 



(2) No such partial zones or "false rings" are evident; 

 the wood is practically devoid of annual rings 

 (though microscopic examination of thin sections 

 may show traces). 



(i) Soft wood ; no heart-wood formed ; grey (Bombax 

 type) : 



e.g. Bombax malabaricum, Mango, 

 (ii) Heart-wood usually present, and the woods denser 

 and less porous : 



e.g. Albizzia Lebbek, Schima Wallichii, 

 Zizyphusjujuba, Tamarixarticulata, 

 Adina cordifolia^ Dipterocarpus 

 tuberculatus, &c. 



B. DICOTYLEDONS in which the annual rings are always dis- 

 tinguishable, and usually obvious, though they may be very 

 narrow. These rings are marked in two chief ways, and a 

 little practice enables the student to distinguish them easily 

 in most cases. 



(a] The annual rings are particularly clear, because the 

 vessels in the spring wood are either larger than 



