292 F. Stoivard: Action of Chemicals on Potato-Tubers. 



tliis and succeeding figures indicate the position of 

 the bud. 



Expt. 2. — Cross section of blight-free tuber after steeping 

 20 hours in 10 % H0S04 and methyl orange. It will 

 be noted that the entry of the acid is exclusively con- 

 fined to the buds. 



Expt. 3, 4, 5. — Cross section of blight infested tubers after 

 20 hours steeping in 10 % H2S04 and methyl orange. 

 The points of entry of the acid through portions of 

 the skin damaged by the ravages of the blight fungus 

 are shown. 



