31 



Note I. From the following experiments made by Mr. C. F. 

 Eckart it will be seen that treatment with corrosive sublimate solu- 

 tion is the most effective cure for seed-cane containing eggs of leaf- 

 hopper, since it does not injure this seed. 



RELATIVE RESISTANCE OF LEAF-HOPPER EGGS TO 

 HYDROCYANIC ACID GAS, CORROSIVE SUBLI- 

 MATE, AND CARBOLIC ACID. 



Sections of cane, eight inches long, were cut from badly affected 

 one-year old cane. The sections were selected as a rule, from the 

 youngest parts of the sticks, and only such portions were taken 

 as bore evidence of hopper eggs having been recentlv deposited. 

 The pieces of cane so selected w^ere then well mixed and lots of ten 

 sections were taken at random for use in each of several experi- 

 ments. 



The treatment to which the several lots of cane were subjected 

 was as follows : 



(i) Immersion in i^ solution of corrosive sublimate for 3 liours. 

 (2} '*' " i^ solution of corrosive sublimate for 6 " 



(3) ■' " 2;/, solution of corrosive sublimate for 3 " 



(4) " "' li solution of carbolic acid for 3 "' 



(5) " ■'' I'/c solution of carbolic acid for 6 " 



(6) " " 2'/c solution of carbolic acid for 3 " 



(7) Fumigation for 24 hou rs with Hydrocyanic Acid 



Gas (one ounce of Cyanide of Potassium for 27 cu. 

 ft of space). 



(8) Untreated cane (8 sections). 



