OF THE STRUCTURE OF WOOD AND HERBS. 



93 



MALLACA. A portion of a cross section of a species of Bamboo, found in the 

 Mallaca isles, from whence its name is derived, is exhibited in figure 140, mag- 

 nified one hundred and fifty times. The five large rings are bundles of vessels 

 running lengthwise through the trunk, the vessels of each forming by their 

 mutual arrangement five tubes (a a a a a) of considerable size, which traverse 

 the bundles through the centre from end to epd. So porous is the stalk of the 

 Mallaca, that by applying the mouth to one end of a stem several feet in length, 

 a lighted lamp placed at the other extremity can almost be extinguished by the 

 impulse of the breath, blown through the stalk ; nor is this surprising, for the 

 large vessels (a a a a a) are one-seventieth part of an inch in diameter. The 

 vessels composing the rings are evidently far inferior in size to the tubes ; and 

 upon actual measurement the greatest are found not to exceed one-five-hun- 

 dredth of an inch in diameter. An elaborate net-work of cellular tissue (6 b) 

 twines around and among th'e cylindrical clusters of vessels, and binds them 

 firmly together with its delicate but strong cordage. 



In figure 141 is exhibited a drawing of a cross section of the common Larch, 



Fig. 141. 



