MICROSCOPIC STRUCTURE 129 



The illustration (Fig. 37) is taken from 

 a photo-micrograph of 32 diameters ; the 

 time of exposure was 5 minutes ; the focal 

 distance was 48 inches ; and the objective 

 used was the inch and a half. 



Looking more closely at the section we see 

 certain dark portions at intervals on the 

 margin ; these are the bases of the leaves ; 

 next comes the bark; pointing towards the 

 centre are radiating plates of wood with 

 large air passages ; between these and the 

 bark are plates of wood running concentrically 

 with the bark; these are held loosely together 

 by soft, medullary processes. In the centre 

 is the cellular pith. 



This is an example of an aberrant exoge- 

 nous stem. 



Calamus Rotang. 



The Calamus rotang is one of the chief 

 species of palms that furnish the canes and 

 rattans used in this and other countries for 

 bottoms of chairs, couches, sides of carriages, 

 and similar purposes. 



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