MAWVAL FOE SUGAR GROWERS. 5 



tube, in others a fine thread is wound in a spiral 

 throughout the length of the tube, while others pre- 

 sent the appearance of being perforated with minute 

 holes. These thin-walled long cells are known as 

 vessels, and are named, according to the markings 

 on their walls, annular or ringed vessels, spiral ves- 

 sels, dotted vessels, etc. Lying round these vessels 

 just described will be seen a number of long thread- 

 like cells, the walls of which are thicker and display 

 no particular marking ; these cells are generally of 

 smaller diameter than the vessels, and the walls are 

 considerably thickened ; they are commonly spoken 

 of as fibres or fibrous cells : hence the collection of 

 fibres and vessels which has been described is gen- 

 erally known as a fibro-vascular bundle, and these 

 bundles will be found traversing the cellular tissue 

 in all parts of the plant. 



When vegetable tissues are burned one portion 

 disappears in the form of gas or vapour, while a small 

 portion remains behind as ash ; the portion which 

 disappears is composed of the elements carbon, hy- 

 drogen, oxygen, nitrogen, with some of the sulj^hur ; 

 the ash contains the remaining elements mentioned 

 in the list on page 2 ; these are combined with oxy- 

 gen, and are generally spoken of as mineral constit- 

 uents, or sometimes as ash constituents. These facts 

 are familiar to planters from burning megass. 



The walls of the cells already described are com- 

 posed of carbon, hydrogen, and oxygen arranged 

 in the following proportions, CeHj„0„" forming a 



* Inspection will sliow that this substance is composed of six 

 equivalents of carbon with five equivalents of water. These com- 



