20 GOURD. [CH. II 



reserve matters contained in the cotyledons, it will be 

 sufficient to call attention to one class of food the 

 carbohydrates. If a thin section of the cotyledon is cut, 

 the cells which make up its tissue are found to be 

 crowded with starch grains which give the characteristic 

 blue colour with iodine 1 . The large quantity of starch in 

 the cotyledons may be roughly gauged by a simpler test, 

 namely, by touching the cut surface with iodine solution, 

 when the whole mass becomes dark blue or almost black. 

 Further details about starch are given in the section 

 devoted to the potato. 



Gourd or Pumpkin (Cucurbita). 



The seed of the gourd, shown in Fig. 5, is flattened, 

 oval in outline and marked with a characteristic thickened 

 border. At the square end is the hilum, or scar where 

 the stalk grew, and also the micropyle. The position 

 of this is shown by the outline of the radicle seen 

 through the closely fitting seed-coats, and pointing to a 

 spot close to the hilum. In the gourd, as in the bean, 

 the cavity of the seed is found to be occupied by a young 

 plant and a plant, moreover, consisting of two large flat 

 cotyledons attached opposite one another to a central axis 

 made up of the plumule and radicle. Another resemblance 

 is that here as in the bean the cotyledons contain reserve 

 materials on which the growing plumule and radicle feed 2 . 

 But in other respects the process of germination is 



1 Either the alcoholic tincture or iodine dissolved in potassium 

 iodide solution. 



2 In the gourd, oil takes the place of the starch in the bean. 



