326 PROCEEDINGS OF SECTION D. 



suggestion of using leaden interceptors in the treatment of deep 

 growths, as the greater part of the rays cut off by the leaden inter- 

 ceptors would only reach the superficial structures, and were, therefore, 

 of no value therapeutically for the deeply-situated disease. 



The author exhibited boxes containing specimens of the plants 

 grown from seeds which had been radiumized and grown at the different 

 distances from the radium specimens, mentioned in this lecture; and 

 plants of seeds unradiumized, grown as a control, were also exhibited. 



15.— FOREST CONSERVATION— A NATIONAL DUTY. 



By Elwood Mead, Chairman State Rivers and Water Supply 

 Commission. 



(Abstract.) 



The lecturer, who was born within its limits, gave a most striking 

 and impressive account of the disappearance, within a single generation, 

 of that once-greatest hardwood forest which prevailed from the 

 Alleghanies to the Mississippi and from Canada to the Gulf, and 

 sketched the evils resulting from its destruction. 



Following the removal ot the cover at the head-waters of the rivers, 

 the fertile soil was scoured from the hillsides by the unrestricted run-off 

 of the rainfall, and the rivers silted up to .such an extent that their 

 navigation in summer was rendered difficult, and their flow so impaired 

 that rice growing on the Atlantic seaboard has almost ceased, 



Australia was urged to profit by the sad experience ot America, 

 already also threatened by a timber famine, and in the interests of water 

 supply and irrigation, and of the future supply of timber for industries, 

 to set apart as permanent Government reserves its forest lands. 



Mr. Mead finished his short but valuable address with the pro- 

 nouncement that nothing would contribute more to the ultimate 

 prosperity of the Commonwealth than comprehensive and effective 

 legislation directed to this end. 



16. THE INSENSITIVITY OF THE LIFE-FORMS OF THE 

 POTATO-MOTH TO VARIOUS POISONS. 



By F. Stoward, D.Sc, Governmejit Botanist of Western Australia. 

 One of the most troublesome insect pests, which ravage the 

 potato crops of the Commonwealth, is the Potato Moth (Gelechia 

 operculella). The active agent of infestation is the larva which 

 attacks and defoliates the growing plant. Under faulty cultural 



