THE POTATO ,529 



ing IS that one is juicy and bulky, while the other 

 is dry, and therefore more concentrated. In cook- 

 ing rice we mix water with it, and may thus make 

 a material not very different in composition from 

 potatoes. By drying potatoes they can be made 

 very similar in composition and food value to rice. 

 Considering the two articles as ordinarily pur- 

 chased, 4.5 pounds of raw potatoes and a pound of 

 uncooked rice contain nearly equal weights of 

 each class of nutrients and have about the same 

 nutritive value." 



The manufacturing processes of the potato 

 plant are described in " Bulletin 71 " of the 

 Wyoming Experiment Station, as follows: 



** In order to understand the relation of the leaves 

 to the tubers it is necessary to know that the 

 starches and other food materials which are stored 

 up in the tubers are produced within the leaves 

 through the activity of the contents of the leaf 

 cells when influenced by the action of light. The 

 leaves are green because the cells contain the green 

 bodies technically known as 'chloroplasts.' No 

 plant which lacks ' chloroplasts' is capable of manu- 

 facturing starch. 



"Leaf structure is essentially the same in all 

 plants. A section from the upper to the under 

 side will show on either side an epidermis of flat- 

 tened, colorless cells. The cells immediatly under- 

 neath the upper layer are elongated and closely 

 packed and are known as the palisade tissue. 

 The lower half of the leaves contain nearly spherical 

 cells, rather loosely arranged, with conspicuous 

 air spaces near the lower epidermis. These com- 

 municate freely with the smaller spaces among the 



