SEEDS AND SEEDLINGS. 37 



wash the roots in running water (do not leave any in the soil or lose 

 them in any way), and dry them thoroughly without charring any 

 part. When quite dry and brittle, weigh each lot and obtain the 

 average weight of the solid matter in each plant. Get a piece of 

 squared paper, as in Fig. 21 (spaces representing inches need not, of 

 course, be inches). As the weekly observations proceed, trace two 

 lines across the sheet, one (a continuous line) to show the weight, 

 the other (a dotted line) the height of the seedlings grown in light ; 

 draw two other lines in red ink to show the weight, and height, of the 

 seedlings grown in darkness. 



* (b) Another method is to use Wheat grains, and grow them with the 

 roots in water. From some Wheat count out thirty-six good sound 

 grains, and divide them into batches of a dozen each ; see that the 

 weight of each batch is as nearly as possible the same. Dry one 

 batch (A) arid record the dry weight. Tie a piece of muslin over a 

 tumbler or bowl filled with water, and put a batch (B) of seeds on the 

 surface of the muslin, which should be kept wet. Another plan is to 

 use a piece of flannel, stab twelve holes in it, and in each hole place a 

 seed. Keep the tumbler in a warm, dark place, and renew the water 

 every second or third day. Plant the third batch (c) as in (B), and 

 keep both at about the same temperature, but when the young shoots 

 appear, expose (c) to the light. When the shoots have grown several 

 inches, carefully remove the seedlings from (B) and (c), noting the 

 difference in colour between the two sets. Dry them thoroughly, 

 without charring even the finest rootlet, and then weigh each lot and 

 compare the weights of (A), (B), and (c). 



65. The Bean Seed contains Food. The results of 

 these experiments will show that a seedling kept in dark- 

 ness loses in dry weight, so that, apart from water, it 

 actually weighs less than the seed itself did, and 



eventually it dies. It is obvious that this loss must be 

 largely due to respiration, and that it is chiefly a loss of 

 carbon in the form of carbon dioxide. The seed must, there- 

 fore, contain a store of carbon in some form, and it is at the 

 expense of this stored carbon that the darkened seedling 

 respires and grows. On the other hand, seedlings grown in 

 the light increase in dry weight, and are therefore able not 

 only to repair the loss due to respiration, but also to add to 

 their dry weight in some way. 



To repair the waste due to respiration and to provide ma- 

 terial and energy for growth, the young plant in a seed 

 requires a store of food upon which it can draw during the 

 early stages of germination. Where and in what form is 

 this food stored, how is it made use of, and how does it 



