author's abstract of this paper issued 

 by t^e bibliographic service, june 2 



PROLONGATION OF LIFE OF TRIBOLIUM CON- 



FUSUM APPARENTLY DUE TO SMALL 



DOSES OF X-RAYS 



WHEELER P. DAVEY 



FOUK FIGURES 



In a previous article^ experiments were described which 

 showed, 1) that x-rays, when given in sufficient quantity, were 

 able to shorten the life of Tribolium confusum, and 2) that the 

 length of life after x-raying could be expressed by a mathematical 

 formula, the theoretical derivation of which was given. It is the 

 purpose of this article to give the results of further experiments 

 showing that it is apparently possible to lengthen materially the 

 life of Tribolium confusum by giving sufficiently small doses of 

 x-rays. 



In the article quoted above curves were given showing that 



MAM 



the minimum dose necessary to kill all the beetles was 500 — ^^-;- 



at 50 KV.2 Some of the less resistant beetles could be killed by 



MAM 



smaller doses, but the curves for 100 and 200 at 50 KV. 



25^ 



had portions in which the death rate was lower than that of the 

 controls. Comment on this was reserved until it could be con- 

 firmed by further experiments. Ample confirmation has now 

 been obtained. 



The experiments undertaken fall into two groups: A, those 

 in which very small doses of x-rays were given daily throughout 

 the life of the beetles; B, those in which the x-ray dose was given 

 all at one time, as in the work previously published. In each of 



' Journal of Experimenta! Zoology, vol. 22, no. 3, April, 1917. 

 - I.e., 500 milliampere-minutes at 25 cm. dLstance at 50 'root-mean square' 

 kilovolts. 



447 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 28. NO 3 



