Changes in Total Peripheral Resistance. 193 



the principal lesions observed are marked atrophy of the skeletal 

 musculature everywhere, and sometimes darkening of mucosa of 

 the large intestine and cloaca; unabsorbed lead bullets, if any, 

 being found in the gizzard. 



The results on 63 animals to date may be briefly summarized 

 as follows: The lethal dose of lead was found to be about 0.16 

 gm. per kilo; time of death in fatal cases was 21 days; time of 

 recovery in survival cases was 26 days to 8 months; lead ab- 

 sorbed in fatal cases was 85 per cent.; concentration of lead 

 in tissues of fatal cases was about 0.075 per cent.; and the 

 current of lead, about 0.0103 gm. per kilo per diem for 83 

 days to 0.02 gm. per kilo per diem for 25 days; the maximal 

 loss of body weight in fatal cases was 40 per cent., in surviving 

 pigeons 8 per cent. ; the first appearance of loss of body weight in 

 all animals was demonstrable at end of 2 to 4 days after adminis- 

 tration and the greatest loss of body weight occurred at the end of 

 20 days; loss of body weight proceeded or was parallel with dimin- 

 ished food intake apparently due to loss of appetite from sickness; 

 the daily food intake was 3.9 gm. in fatal cases and 18 gm. in 

 survival cases; the normal food intake being 23 gms. 



All of the above factors were beneficially influenced by the 

 administration of sodium iodide in food and water and magnesium 

 sulphate and calcium sulphide in food, while sodium chloride 

 administered in the same way was not beneficial. 



The following lead salts administered in doses whose lead 

 content was 2 to 13 times that of the minimal fatal dose of metallic 

 lead were non-toxic: lead chloride, lead iodide, lead acetate and 

 lead sulphide. 



Of the following metals used in 2 1/5 times the dosage of the 

 minimal fatal dose of lead, namely, zinc, copper, tin, bismuth, 

 iron and cadmium, only cadmium, bismuth and zinc were toxic, 

 but not fatal during a period of 27 days of observation. Therefore, 

 lead is decidedly more toxic, and plumbism is more or less a 

 specific toxicity in the sense that symptoms occur promptly and 

 in a striking manner, the motoi effects and fatalities being absent 

 with cadmium, bismuth and zinc. 



1 Presented at the thirty-first meeting of the Pacific Coast Branch, December 

 15, 1921. 



