394 LIFE ON THE EARTH 



pumpkin, squash, bean, corn, and drop on to the inside of each a few 

 drops of the iodine solution made in Experiment 120. Do the 

 seeds show the presence of starch ? 



Experiment 126. Soak some beans for about twenty-four hours. 

 Rub off the skin from two or three and examine their different parts 

 carefully. Plant the beans in a box of damp sawdust. Put the 

 box in a warm place. Plant some corn that has been soaked for 

 two or three days in the same box. After the seeds have been 

 planted several days, carefully remove a bean and a grain of corn 

 and examine. Make a sketch of each of the seeds. 



After a few days more remove another seed of each and examine 

 and sketch. Continue to do this until the little plants have be- 

 come quite well grown. Do the two seeds 

 develop alike? Which of the seeds has two 

 similar parts? These two parts are called 

 cotyledons. What appears to be the use of these 

 parts to the sprout? Consult the results of 

 Experiment 124. Note the root development 

 in each seed and the stem development. The 

 sprouts get their food from the seed. 



When we examined the different seeds 

 in Experiment 125, we found that they 

 each contained starch. When the seeds 

 were soaked and planted, we found that 

 a part of the seeds began to grow, form- 



FlGURE 128 



ing a sprout. Inis part is the embryo 

 already described. We also saw that the bean seed divided 

 into two like parts which gradually withered and shrank, 

 as the sprout grew, while the corn had only one such part. 



These parts are called cotyledons, or seed leaves. The 

 bean seed (Figure 128) is a dicotyledon (two seed leaves) 

 and the corn a monocotyledon (one seed leaf). These coty- 

 ledons are the food storehouses for the germinating seed. 

 As the sprout grew, the root, with its root hairs, developed, 



