[Proc. Roy. Soc. Victoria, 24 (X.S.). Pt. 11.. 1911. J 



Art. XX. — The Effect of Certain Chemical Substances 

 on the Vitality of the Buds of Potato-Tubers, and 

 their Disinfect h.-e Action on Potato Blight {Phyto- 

 phthora infestans). 



By FREDERICK 8T0WARD, D.Sc. 



(Government Botanist, Western Australia). 



(Commnnicated by Alfred J. Ewart, D.Sc, Ph.D., F.L.S.) 



(With Plates LVII.-LX.). 



[Read 2nd November, 1911.] 



The treatment of potatoes, destined to serve as seed tubers^ 

 by immersion in aqueous solutions of various antiseptic re- 

 agents, as a pre<ventive means against certain disease-producing 

 organisms, chiefly parasitic fungi, is a practice which i& 

 gradually becoming more and more general. 



The basis of the practice, at least in the hands of the majority 

 of potato growers, is largely if not completely empirical. The 

 criteria usually relied upon as to the effectiveness or success 

 of this or that method of treatment against potato diseases 

 and their dissemination, are essentially based on the crop- 

 yield, and its comparative freedom from the disease which the^ 

 treatment is tentatively designed to lessen or even eliminate. 



Although broadly recognised as essentially antiseptic, or 

 under certain conditions toxic in their action, little attention 

 appears to have been devoted to the study of either the mode 

 of action on, or the possible penetration of these reagents into, 

 the tissue of the tuber : whether, for example, penetration of 

 these chemical substances does or does not take place, and if 

 the former alternative holds, whether penetration occurs ex- 

 clusively through the skin, or through both buds and skin ; 

 or whether under certain conditions their action, though at 

 first it may be effective and beneficial, becomes decidedly harm- 

 ful, etc. 



