Microscopical Essays. 66g 



cool houfe-Ieek, and the fiery muftard, the nourifhing grain, and 

 the deadly night-fhade. 



The wood may be confidered as compofed of two parts, lig- 

 nous and parenchyraous. We have already treated of the 

 former; the latter is that which is difpofed into rays running as 

 it were between the lignous fibres, and interweaving with them; 

 k originates either with the pith or corona. There is a very 

 great diverfity in thefe radial infertions, in fome trees there are 

 very few, while they abound in others ; in fome they are very 

 fine, in others very thick. In texture they feem fimilar to 

 the blebs of the bark, only that here they, are fo crouded and 

 firetched out as to appear like parallel threads* fomething fimilar 

 to a net when drawn tight. 



Of the Corona, 



Dr. Hill gives this name to that circle which furrounds the 

 pith, and feparates it from the wood; although in his opinion it 

 differs greatly from both, and in it's compofition has no refem- 

 blance to either. It is, according to him, the moft important 

 part in the whole vegetable fabric, by which the propagation, and 

 mcreafe of the branches, buds, and {hoots, is carried on. * 



It has been ufual to fuppofe the pith of vegetables to be the 

 part in which thefe wonderful fources of increafe refides, but this 

 is not the cafe ; and he afferts, that fo far from being prior to the 

 other parts, it is in reality pofterior to fome of them. 



The 



* Hill on the -Conftru&ion of Timber, p. 55, 



