The Tobacco Plant 107 



six or eight weeks' time tlie tobacco assumes a warm, 

 brown colour, though it is still flavourless. The 

 essential fragrance of tobacco is produced by fermen- 

 tation. 



To understand this process some knowledge must 

 be had of the leaf. It consists of three parts — the 

 upper skin, the lower skin, and the intervening cells. 

 The upper cuticle is a thin, transparent, colourless, 

 tough substance, very like waxed tissue-paper. The 

 lower cuticle is a similar but coarser skin with tiny, 

 short, bulbous protuberances. Between the two skins 

 is a honeycomb-like collection of cells containing sap. 

 It is this sap which gives the colour, flavour and 

 taste to tobacco ; the skin is merely an envelope, 

 and, burnt, forms the ashes. 



At first in the growing plant the sap is a pale 

 green ; as the plant matures it becomes a bright 

 emerald, and later of an olive shade. In the sweat- 

 ing process the sap is decomposed by the heat into 

 a thick, viscid gum of a brown colour. The final 

 process of fermentation evolves the flavour of the 

 tobacco. 



When by ' sweating ' the leaves have become 

 warmish brown, they are formed into bundles of six 

 or ten leaves, secured by a leaf. These ' hands ' are 

 collected and stacked. The inherent heat and mois- 

 ture of the closely-massed leaves sets up fermenta- 

 tion and the tobacco undergoes a radical change. 

 To prevent the mass of tobacco reaching too great 

 heat (90° is the limit), it is constantly stirred, the 

 inmost hands being brought to the edge. Various 

 mixtures are used to promote fermentation and pro- 



