26 POTATO. [CH. II 



shall contain an "eye." The eyes of the potato are 

 little crumpled or withered looking nodules sunk in 

 depressions on the surface, which the unwary might pass 

 over as diseased spots, or as due to other casual injury. 

 The bud-like character is apparent on cutting a section 

 (at right angles to the surface of the potato) through the 

 eye; such a section shows a dwarf stem and very small 

 leaves. The scars which occur at the eyes are the remains 

 of rudimentary scale-like leaves, which are plainly visible 

 in the young tuber. The fact that the " eyes " grow in the 

 angles (axils) of these leaves is another point demonstrating 

 the stem-like character of the potato. This point is more 

 fully dealt with in Chapter IV. 



There is one point which strikes the observer who 

 compares the growth of a potato bud with that of a seed : 

 namely, that in the bean there is a radicle ready to grow 

 into the root-system of the plant, whereas in the potato-eye 

 there is a young stem but no young root. Nevertheless 

 the potato plant, which grows out of the eye, has roots, 

 and the question whence they come has to be answered. 

 They will be found to grow out of the stem of the 

 developing plant. When this occurs the growth is called 

 adventitious. A familiar example of adventitious roots is 

 to be found in the ivy, where the roots, by which the plant 

 adheres to and clambers up a wall or tree, grow out of the 

 branches, as shown in fig. 9. 



With regard to the nature of the food-stores in the 

 potato we shall only consider the carbohydrate part of 

 the reserve namely, the starch. The potato is one of 

 the commercial sources of starch, supplying, for example, 



