26 STRUCTURAL BOTANY 



b. The Fruit 



The fruit is the ripened pistil, and contains 

 the seeds, which are the ripened ovules. It con- 

 tinues to show the same general structure as the 

 pistil, but grows much larger, and undergoes some 

 important changes, a description of which will be 

 found on p. 137. During the development of the 

 pistil into the fruit all the other floral organs calyx, 

 corolla, and stamens- drop off. 



II. INTERNAL STRUCTURE 



A. THE CELLS 



If we examine under the microscope a thin slice, 

 or section as it is called, from any part of an 

 ordinary plant, say, for example, a section cut straight 

 across the stem of a Wallflower, we find that its 

 substance is not uniform, but is divided up by a 

 network of walls into innumerable minute chambers 

 of varying size and shape (see Fig. 20, p. 48). If we 

 make another section at right angles to the first, 

 say a section lengthways through the stem, we find 

 the same structure, except that in this view the 

 chambers appear to have somewhat different shapes 

 (see Fig. 22, p. 52). Combining the two views together, 

 we come to the conclusion that the whole substance 

 of the plant is composed of a system of closed 

 compartments. This is the reason why, if a juicy 

 fruit like the melon is cut into pieces, all the juice 



