222 MINNESOTA BOTANICAL STUDIES. 



Description of Plates. 



Plate VII. 

 The Anderson registering balance set up to weigh transpired water. 



Plate VIII. 

 The Frost electric auxanometer in use to determine growth in length. 



Plate IX. 

 The Frost time-recorder. 



Plate X. 



The Frost auxanometer connected with recorder. 



Fiwn photographs by Professor Wm. R. Appleby. 



