274 TIMBEES AND THEIE USES 



elements, bast parencliyma, sieve tubes and 

 companion cells, compose tlie soft bast. The 

 bast fibres are very long narrow cells with much 

 thickened walls, so much so at times that they 

 are almost solid ; on their lateral walls there are 

 many unthickened places which appear as trans- 

 parent spots when magnified; these are known 

 as pits. The bast parenchyma consists of rows 

 of several slightly elongated cells each one of 

 which contains protoplasm and often starch. 

 The sieve tubes are the vessels through which 

 the elaborated food material passes ; they are 

 composed of vertical rows of elongated cells 

 whose end walls are perforated by numerous 

 pits, hence they are termed sieve plates; they 

 contain protoplasm. The companion cells are 

 so called because they are always adjacent to 

 the sieve tubes ; they contain' protoplasm and 

 their walls exhibit no pits or perforations of 

 any kind. Companion cells are not to be found 

 in the bast of conifers. 



It is the custom to deride the use of the 

 microscope as an aid to the study of timber. 

 True the microscope will not and cannot tell 

 us much that we would know concerning wood, 

 but it will at least help towards a better under- 

 standing of the reason why certain woods are 

 more suitable for certain purposes than other 

 apparently closely alUed woods. The micro- 



