94 J. A, ARCHER ON TOBACCO. 



6. Chicory. — In a' transverse section of chicory, tlie vascular 

 tissue is arranged in the form of oval bundles. The hairs are 

 long and of a complicated structure, each joint being made up 

 of small cells, the last joint generally terminating in a bulb. {Fig. 

 '7,pL 5.) 



7. Cabbage. — This is distinguished from tobacco by its vascular 

 tissue being in the form of wedged -shaped bundles. 



8. Potatoe. — The horseshoe here is very like that in tobacco, but 

 smaller ; but the hairs, which have from two to seven joints, are 

 all pointed. 



9. Henbane. — This is more like tobacco in microscopical struc- 

 ture than any other leaf at present known. Its horseshoe is 

 small, but resembles that in a small tobacco leaf; its hairs are 

 jointed, the first joint being similar to the first joint in tobacco, 

 and the hairs frequently terminate with a bulb. A little expe- 

 rience, however, renders it easy of detection : — thus the hairs ap- 

 pear very transparent and very weak, each hair being folded on 

 itself ; so that it is difficult to see from top to bottom the whole of 

 one side of the hair. Again, the bulb on the end is devoid of granu- 

 lar matter. Lastly, another kind of hair is frequently met with — 

 namely, a jointed hair, with a long filament or whip. This of 

 itself is sufficient to distinguish it from tobacco. 



10. Foxglove. — The character of the hairs is shewn in Jig. 8 ; 

 they are easily distinguishable from the hairs on the tobacco plant. 

 Foxglove is but rarely used as an adulterant. 



Thorn apple, potatoe, aiid henbane belong to the natural 

 order Solanaceee, to which tobacco also belongs, and they 

 present the closest approach in appearance to that plant. It will 

 be seen, however, that distinguishing features exist which can easily 

 be detected by the aid of the microscope, and not only the kind 

 but the proportion of adulteration exactly determined. 



Most of the other adulterations previously mentioned are detected 

 by chemical means. 



