91 



On Tobacco. By J. A. Archer. 



(Read June 26th, 1868.; 



(Abstract.) 



After enumerating the different qualities of leaf tobacco, chiefly, 

 it would seem, arising from the climate and. soil of the place of 

 growth, the paper proceeded to describe the method of culture, 

 resembling, in many respects, the procedure followed in raising 

 vegetables in our own market gardens. The chief enemy of the 

 growing plant seems to be what is called the " horn worm." This 

 is the larva of one of the Sphingidee, or hawk moths, described as 

 the Sphinx Carolina, an insect of four inches and a half expanse of 

 wing. These caterpillars are said to cause great damage to the 

 crop. 



"When the crop is cut, the leaves and stems are partially dried, 

 then allowed to ferment in heaps, and subsecpiently cured, or more 

 completely dried. The tobacco is then packed under pressure, 

 and conveyed to the various markets. 



Tobacco contains the peculiar element, nicotianin, which gives 

 the peculiar odour, and nicotine, an alkaloid, combined with gum, 

 tannin, gallic acid, resin, and other vegetable products. The 

 burnt ash gives potash, soda, lime, magnesia, chloride of sodium 

 and potassium, phosphate and sulphate of lime and silica. 



A transverse section of the midrib, or any of the veins in 

 the leaf, exhibits, under the microscope, the appearance of 

 a horseshoe, surrounded on all sides by cellular tissue {Fig. 1, 

 Plate 5). The horseshoe is made up of the cut extremities of the 

 spiral or pitted tissue, which gives strength to the stalk. On the 

 outer surface are numerous hairs, of peculiar form — one of the 

 principal indications with the excise for detecting the admixture of 

 other leaves by the manufacturers. These hairs vary in size, are 

 tubular, and composed of several cells joined together (generally 

 from four to six), the terminal one, in most instances, having a 

 gland attached, consisting of one or more small cells, filled with 

 dark granular matter, and the basal cell is mostly much longer than 

 the other. Sometimes a few hairs may be found with an obtuse 

 rounded extremity, without the gland. Occasionally there are a 



