Action of Chemicals on Potato-Tuhers. 291 



also through those parts of the skin which have been 

 damaged by the ravages of fungus, or other parasitic 

 organisms. 

 (4) It is essential to add that the results so far related in 

 regard to the storage qualities possessed by acid 

 treated tubers refer solely to the results obtained 

 with fully matured, sound tubers. 



It is hoped that facilities will shortly be provided for the 

 further prosecution of this investigation, 



I desire to express my acknowledgments to my colleagues, 

 Mr. A. J. Despeissis, Commissioner for Tropical Agriculture, for 

 his interest, suggestions, and valuable criticism ; and to Mr. 

 L. J. Newman (Entomologist) for loyal and intelligent assistance 

 during the progress of this investigation. My best thanks are 

 also due to Mr. Pether, Government Lithographer, Perth, for 

 the series of excellent illustrative photographs, which he has 

 been good enough to prepare from his negatives. 



EXPLANATION OF PLATES. 

 Platk LVIL 



Mature Victorian thick-skinned tubers, 10 % H.2S04 treatment; 

 experiments 5, 6, 7, storage tests. 



Plate LVIII. 



Mature Victorian thick-skinned tubers, 10 % H.S04 treatment; 

 experiments 5, 6, 7a, and untreated control planting tests. 



Platk LIX. 



Mature Victorian thick-skinned tubers, 10 % H.2S04 ti-eatment, 

 experimenting 7, planting test. Three tubers on removal 

 from soil 40 days after planting. 



Platk LX. 



Entry of acid into blight-free and blight-infested tubers. 



Expt. 1. — Cross section of blight-free tuber after steeping 

 20 hours in aqueous methyl orange. The arrows in 



