60 



EXPERIMENTS WITH PLANTS 



in the Bean, Pea or other seeds ? 

 (See Fig. 22.) 



The surprising amount of force 

 developed by swelling seeds is ob-. 

 viously connected with the absorp- 

 tion of water, by means of which 

 they increase in size. It is very 

 easy to construct an apparatus in 

 which the absorption of water will 

 generate pressure just as 

 it does in the seed. For 

 this purpose we take a 

 piece of glass tubing about 

 one -sixteenth of an 



T 



inch in diameter (in- 

 side), or a little larger; 

 smooth one end by heat- 

 ing in a flame Until it 49 - Buckeye. A stiU later stage. 



fuses slightly, and when it has cooled stretch over it a 

 piece of ox -bladder or heavy parchment paper (ob- 

 tainable of druggists). Hold the 

 piece of bladder stretched like a 

 drum -head across the mouth of 

 the tube, and let an assistant wind 

 it tightly clear to the tube's mouth 

 .with ordinary cotton twine; tie it 

 50. scarlet Runner Bean with a square knot and let it soak 



germinating; the cover /, , , , , . , 



split across. for several hours, during which 



