MICROSCOPIC OBJECTS. 32 



Fig. 63. Transverse Section of Honduras Mahogany 

 (Swietenia Mahagoni) , x 80. Exogen. 



This section also shows the resin in its natural position 

 in the ducts. The transverse sections of the ducts and the 

 prosenchymatous tissue also exhibit nearly as open an ap- 

 pearance as seen in the longitudinal sections. 



This wood is largely used in commerce. 



Fig. 64. Longitudinal Section of Alder-wood ( Alnus 

 glutinosa), x 200. Exogen. 



The medullary cells are of a very dark and close structure 

 in this wood, which will be seen on referring to the drawing ; 

 the prosenchymatous tissue is also of a close nature ; but to 

 make up for this, and to allow the juices of the tree to circu- 

 late freely, it has rather large ducts. 



The wood is extremely useful, having the property of re- 

 maining nearly intact for many years under water. It is 

 therefore used for piles &c ; it is also used for the produc- 

 tion of charcoal &c. 



