SEEDS AND FRUITS. 1 35 



for example, from the endosperm of castor-oil, shows them in the 

 form of oval bodies crowding the small parenchymatous cells. 

 Each grain contains a crystalloid and also a rounded mass of 

 mineral matter known as a globoid. A microscopic section 

 through the cotyledon of a ripe pea shows that here numerous 

 minute aleurone grains are associated with far larger oval starch 

 grains. In wheat the external layer of endosperm cells contains 

 aleurone only, the internal part starch only. The preparation of 

 flour for white bread involves the removal of this external highly 

 nutritious layer. Hence the value of whole flour bread where it- 

 still remains (cf. p. 26). 



Starch is by far the commonest reserve material in seeds, and 

 grains differ in shape according to the kind of seed. Hence 

 the adulteration of flour, &c, can be detected by means of the 

 microscope. 



Fruits are seed-containing structures resulting from a growth 

 of the ovary, and sometimes other parts, which follows fertiliza- 

 tion. The terms superior, inferior, apocarpous, and syncarpous, 

 are used here in the same sense as when dealing with the pistil 

 (pp. 100, 101). A distinction is made between (1.) true fruits, 

 developed from ovary alone, and (2.) spurious or false fruit* 

 (pseudocarps), which involve other structures as well. 



I. Spurious Fruits. — These necessarily consist of one or more 

 true fruits or developed ovaries surrounded by or imbedded in 

 other structures. An entire flower cluster sometimes gives rise 

 to a single fruit, termed in this case multiple or collect ire. Fig, 

 pine apple, and mulberry are the commonest examples. 



The flesh of a fig (lag. 34), for instance, is the succulent 

 common receptacle, and the " seeds " within it are the true 

 fruits. The term "fruit" does not necessarily imply edibility, 

 from a botanical point of view at least. Again, each 

 of the little red swellings making up a mulberry (fig. 

 55) is simply the calyx of a flower become juicy 

 and surrounding a small hard fruit. The pine-apple 

 is developed from a spike of small crowded flowers, 

 the ovaries and floral receptacles of which have 

 fused with bracts and axis into a fleshy mass. Each 

 lozenge-shaped area in the outside corresponds to 

 a single flower. Seeds are absent as a result of ^fifShmJ? 

 cultivation. 



Aggregate fruits are formed in another way in beech and sweet 

 chestnut. Here the " nuts " are true fruits, and the prickly husk 

 in which they are enclosed is formed by bracts which have en- 

 larged and grown over them. 



The best types of spurious fruits formed from a single flower 



