DICOTYLEDONS SOLANACEJ2 DIAGRAM 13. 177 



always simple, with five indentations ; and the corolla is similar. 

 Lastly, there are five stamens, which in the potato and the night- 

 shade, are perforated with a small hole, through which the pollen 

 es'capes. 



The potatoes which we eat are swellings which are formed at 

 different points of the long creeping roots of the plant. These 

 swellings are called tubers ; they are formed by the large quantity 

 of starch which collects there. The starch in potatoes may be 

 extracted by crushing them, and afterwards sifting the bruised 

 pulp in water.. The grains of starch, being very small, pass 

 through the sieve, and sink to the bottom of the vessel by their 

 own weight. 



If a potato-plant is left without being pulled up, the plant dies 

 at the end of the year, but next year each potato produces a new 

 shoot from the hollows which it contains, and which are called 

 eyes. A field of potatoes is always planted with pieces of potato 

 which still contain the eyes. If potatoes are kept in a damp and 

 dark place during the winter, these eyes are seen to bud, and 

 produce long pale filaments, on which pale yellow leaves some- 

 times grow. They are of a yellow colour because they have grown 

 in darkness ; and in order that the leaves of plants may acquire 

 their fine green colour, it is always necessary for them to be 

 exposed to the sun, or at least to daylight. The hearts of 

 cabbages and lettuces are not so green as the leaves surrounding 

 them ; and in the same way, the earth is heaped round celery, that 

 the leaves may remain yellow, and that the light may not turn 

 them green. The parts which thus remain yellow are also more 

 tender. 



In the Tobacco, the leaves are used for the very general practices 

 of smoking, chewing, and snuffing. The leaves are pulled off, and 

 allowed to dry; when they are yellow, they undergo some 

 preparation, and are then rolled up to make cigars, or chopped to 

 make smoking tobacco, or powdered to make snuff. The use of 

 tobacco is never indispensable ; it can always be given up, and it 

 is often injurious to those who are addicted to it. The flowers of 



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