38 KXrERBIEXT STATION. [Jan. 



Sawdust treated with creosote proved to be one of the best 

 substances for checking the development of the roots. In all 

 but a few cases the roots in direct contact with the sawdust 

 were killed, although in one instance, where the sawdust was 

 not compacted enough, one root developed along the side of the 

 pot without being injured. Where the saw^dust was well com- 

 pacted in the pots all the roots which came into contact with it 

 were killed. 



The excelsior and creosote Avere fully as eifective as the saw- 

 dust. The excelsior, however, being more loosely compacted, 

 allowed some roots to penetrate further into it before being 

 killed than was the case with the sawdust, but in no case did 

 any of the roots penetrate through or around, the excelsior 

 through the hole in the bottom of the pot. 



Kot quite as good, results were obtained from the use of 

 excelsior and Carbolineum and sawdust and Carbolineum as 

 with excelsior and creosote and sawdust and creosote. Both 

 the excelsior and sawdust retained the creosote the best, as was 

 evident from the color and odor as well as from the results 

 of root killing and penetration. A greater compactness of 

 both the sawdust and excelsior would undoubtedly prove even 

 more effectual in preventing root growth. 



The substances, arranued as re£>ards their degree of effi- 

 ciency, may be grouped as follows : — 



Excelsior and creosote. 

 Sawdust and creosote. 

 Excelsior and Carbolinevun. 

 Sawdust and Carbolineum. 

 Cocoa fiber and creosote. 

 Asbestos and creosote. 

 Oakum and creosote. 



The sodium arsenate treatments were all failures, as this 

 substance seemed to wash out very quickly, and in one case, 

 where asbestos was treated with creosote, 40 per cent, of the 

 roots passed through the hole in the bottom of the pot. 



Xo better results were obtained with asbestos and Carbo- 

 lineum. 



C^ocoa fiber failed 1o absorb and retain the chemicals any 



