180 MINNESOTA BOTANICAL STUDIES. 



the exterior by means of a light brass tube. One scale pan 

 will then be on the outside of the case and can be used for the 

 growing fruit. 



In the preliminary experiments on transpiration this appa- 

 ratus has been found to eliminate a large proportion of the 

 errors usually attending this work, while it is of equal value in 

 work on growth increase of weight. 



See Plate VII 



