4 EXPERIMENTAL PLANT PHYSIOLOGY. 



EXPERIMENT 55. 



ACTION OF DIASTASE. 



Place 10 grams of seed of Barley in a germinator for 36 hours, 

 or until the radicles are .5 cm. in length. Grind fine, in an ordi- 

 nary coffee-mill, and add to three parts of water. After a time filter 

 and mix the filtrate, which now contains diastase, with a fifth part 

 of very thin starch paste (i gram starch, 100 grams- water). A 

 sample of this mixture is colored blue on treatment with iodine, a 

 sample taken later, violet, then brown, and finally one taken after 

 two or three hours is colorless, demonstrating that all the starch 

 has been transformed into maltose or sugar by the diastase present 

 in the germinated seed. 



Cut thin sections of the seeds at the beginning of the experiment 

 and determine the appearance and characteristics of the starch- 

 grains. Make a similar examination 24 and 48 hours later. Allow 

 germination to proceed in a few seeds, and examine 4 days later. 

 The starch-grains are gradually corroded and dissolved by the 

 diastase formed. 



EXPERIMENT 56. 



TRANSLOCATION OF STARCH. 



A Tropaeolum plant whose leaves are rich in starch is placed in 

 the dark after some of its leaves have been cut off. The excised 

 leaves are likewise placed in the dark in a moist room or under a 

 bell-jar. After a few days test some of the excised leaves and those 

 remaining on the plant for starch. Those on the plant show some 

 starch, mostly in the nerves, while those excised show starch in the 

 other parts as well, because they could not transfer it to other 

 organs. 



EXPERIMENT 57. 



FORMATION AND TRANSLOCATION OF STARCH. 



On a well-developed plant of Tropaeolum majus standing in the 

 sunlight in the forenoon, darken portions on some healthy leaves, by 

 means of cork plates, fastened on opposite sides by pins. On the 

 afternoon of the following day cut off the leaves and boil in water 

 in a porcelain dish for a few minutes, to kill the protoplasm. Ex- 

 tract the coloring matter by alcohol many times renewed. The de- 

 colorized leaves are now saturated with alcoholic iodine in a porce- 



