146 



ABSORPTION OF RUBIDIUM AND CESIUM 



the rats died in violent tetanic spasms. As a control, the above diet 

 with potassium chloride in amounts equivalent to the rubidium or 

 cesium chlorides was fed to rats with satisfactory results although 

 the same diet plus rubidium or cesium chloride was fatal with the 

 usual symptoms. Moreover a diet in which only one-half of the 

 potassium was replaced by an equivalent amount of cesium or rubid- 

 ium was lethal. In other words the rubidium and cesium in quanti- 

 ties used were toxic, irrespective of the presence or absence of potas- 

 sium. The toxicity of rubidium and cesium was more pronounced 

 than we had expected from the literature dealing with a variety of 

 biological experiments in which these salts have been employed. We 

 have found that as little as 2 cc. of 1.44 per cent solution of rubidium 



TABLE II. 

 The Absorption of Rubidium and Cesium by Rat Tissue. 



*Richly present as shown by spectrum. Amount not measured. 



chloride (a concentration isotonic with 0.7 per cent sodium chloride), 

 injected into the dorsal lymph sack of frogs weighing from 30 to 40 

 gm., killed within 24 hours, while 1 cc. on two successive days was 

 also lethal. Autopsy of the rats revealed nothing of note except 

 in one case showing an infection of the lungs. Various tissues of 

 some of the rats which had been on diets containing rubidium or 

 cesium were decomposed in a mixture of sulphuric and nitric acids. 

 The resulting clear solution was made up to 10 cc. and subjected to 

 spectrum analysis for estimation of rubidium or cesium. Results 

 are summarized in Table II. We satisfied ourselves that these metals 

 were actually contained in the cells by a thorough perfusion through 

 a cannula in the left ventricle of a rat, chloroformed after 10 days 

 on the cesium-containing diet. Potassium-free Ringer solution was 



