SEEDS AND THEIR GERMINATION 395 



and the stem with its leaves. When these had grown strong 

 enough, the cotyledons, having performed their part, dropped 

 off. The plant was now ready to prepare its own food by 

 the aid of the sunlight. 



Experiment 127. Place several beans in a tumbler of damp saw- 

 dust and put it in a warm, light place. Keep the sawdust moistened. 

 After the beans are well sprouted, with a sharp knife cut one of the 

 half beans or cotyledons off from a sprout. Cut both cotyledons 

 off another sprout. Put the sprouts back on the sawdust. Do 

 the sprouts grow as well as those of the other beans ? 



Experiment 128. Fill a 16-ounce, wide-mouth bottle about one 

 third full of peas or beans. Pour in more than enough water to 

 cover them. Tightly cork the bottle and put in a warm, sunny 

 place. Put another similar corked empty bottle beside it. Allow 

 the bottles to stand for several days until the peas have sprouted. 

 Remove the cork from the bottle containing the peas and insert 

 a burning splinter. Do the same to the empty bottle. Why does 

 not the splinter burn as well in each ? If on being placed in either 

 bottle the splinter is smothered out, it shows the presence of carbon 

 dioxide. 



Experiment 129. Fill two 8-ounce, wide-mouth bottles each 

 about one third full of coarse sawdust and fill the remaining part 

 with peas which have been soaked for a day. Pour in sufficient 

 water to cover the sawdust. Cork one of the bottles tightly, leaving 

 the other open. Put the two bottles in a warm, sunny place. 

 Whenever necessary, pour on sufficient water to keep the sawdust 

 in the open bottle wet. In which bottle do the seeds sprout the 

 better? Does air appear to be necessary for the growth of seeds? 

 As determined by the previous experiment, what part of the air 

 is used? 



We found in Experiment 127 that if the cotyledons 

 were cut off before the sprout had become sufficiently 

 mature, it could not continue its growth. In Experiment 

 128 we found that the sprouting seeds took up oxygen 

 from the air and gave out carbon dioxide just as animals 



