288 Dr Brewster on ihe Natural Histori 



o 



"An ounce and a half, treated in this manner, was reduced 

 to an ounce. The process lasted three quarters of an hour. 



" The substance is sent to market in this state, and is taken 

 in powder as a tonic, or chewed with betel, with a view to re- 

 novate the constitution.*" 



From these observations of Dr Wilson, I shall now proceed 

 to give an account of those which I have made upon Tabasheer, 

 including in a very brief form such as I have already published. 



As tabasheer is found only in a small number of bamboos, 

 we cannot regard it as a secretion from the plant in a healthy 

 state. An inteUigent native of Vizagapatam, who had in- 

 spected several hundred bamboos, observed, that in every joint 

 which contained the tabasheer there was a small perforation 

 evidently made by an insect ; and he conceives that the ex- 

 terior juices of the plant find their way through this opening, 

 and drying up form tabasheer. This observation, however, 

 is by no means correct. I have found tabasheer in many joints 

 where there was no perforation ; and as the perforations are 

 never lined with the siliceous matter, and have no accumula- 

 tion of tabasheer at either end, they can have performed no 

 part either in secreting or conveying the juices of the reed. 



An examination of the joint or internode of the bamboo will 

 probably lead us to a more satisfactory explanation. The culm 

 or stalk of the bamboo represented in Plate IV. Fig. 2, by MN, 

 consists of a number of concentric rings. The outer rings, AC, 

 BH, shown in section, are continued through the length of the 

 reed, notwithstanding the little annular protuberance which 

 marks externally the place of the internode AB. The inner 

 rings, DE, GF, however, the innermost of which is a delicate 

 membrane, do not pass onwards, but are interrupted by the 

 internode, and turning round at EF, they form the roof of the 

 cavity DEFG, joining the similar membrane on the side FG. 

 Between AE and FB, where the concentric rings diverge, 

 the space left between them is filled up with a soft spongy mass, 

 which forms the substance of the internode AB. As the sap 

 ascends between AC and ED, it must be stopped partially at 

 the internode between A and E, part of it passing A, and part 

 gf it being either absorbed by the spongy mass between AE, 



