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CHAPTER VII. 



- OF THE MEDULLA OR PITH. 



1 HE centre or heart of the vegetable body, within the 

 wood, contains the Medulla or Pith. This, in parts 

 most endowed with life, as roots, and young growing 

 sterns or branches, is a tolerably firm juicy substance, 

 of an uniform texture, and commonly a pale green or 

 yellowish colour. Such is its appearance in the young 

 shoots of Elder in the spring ; but in the very same 

 branches, fully grown, the pith becomes dry, snow- 

 white, highly cellular, and extremely light, capable of 

 being compressed to almost nothing. So it appears 

 likewise in the common Red or White Currant, and 

 numerous other plants. In many annual stems the 

 pith, abundant and very juicy while they are growing, 

 becomes' little more than a web, lining the hollow of 

 the complete stem, as in some Thistles. Many grasses 

 and umbelliferous plants, as, Conium maculatum or 

 Hemlock, have always hollow steins, lined only with 

 a thin smooth coating of pith, exquisitely delicate and 

 brilliant in its appearance. 



Concerning the nature and functions of this part 

 various opinions have been held. 



Du Hamel considered it as merely cellular substance, 

 connected with what is diffused through the whole 



