Seeds and Seedlings. 15 



with Lima beans, removing the cotyledons from soaked 

 seeds, and planting the much diminished embryos, together 

 with normal seeds, in moist sawdust. Make comparisons 

 of the results of all of the experiments of this kind, and 

 write out your conclusions in full. This experiment will 

 be more certain to succeed if the sawdust has been boiled, 

 to destroy moulds and bacteria. 



40. Soak seeds of barley in water over night, and plant 

 in moist sawdust in a wide-mouth bottle ; place in the 

 bottle a test tube containing a strong solution of pyrogallic 

 acid and caustic potash ; cork the bottle tightly by shov- 

 ing the cork to a short distance below the rim of the 

 bottle and filling in over the cork with melted sealing 

 wax. Prepare another set of seeds in the same way, but 

 with a potash solution only in the test tube. The pyro- 

 gallic acid in its alkaline solution absorbs the oxygen from 

 the atmosphere in the bottle, while the caustic potash in 

 both instances absorbs the carbon dioxide of the atmos- 

 phere, and that which is produced by the germination of 

 the seeds ; the conditions are, then, as follows : one bottle 

 lacks oxygen and carbon dioxide, while the other lacks 

 only the carbon dioxide. The experiment is designed 

 to answer the question whether oxygen is necessary to 

 germination. Let the experiment continue for several 

 days, keeping the bottles in a dark and warm place. 

 Record the results of your observations. 



41. Remove the glass front and the hands from a cheap 

 alarm clock. Provide a soft pine block about an inch 

 square, whittle one end to a taper, and drill a small hole 

 into it, so that it will slip through the opening of the dial 

 face and tightly over the hour-hand spindle. Fasten a 

 Petri 1 dish to y ~. : e outer face of the pine block by a melted 



1 See catalogues of dealers in bacteriological supplies. 



