542 SUTHERLAND SIMPSON" 



excitability is due entirely to lack of calcium in the circulating blood. 

 When an attempt was made to replace the blood of the whole animal 

 with this caMum-poor diffused blood, it was not very successful in in- 

 creasing the excitability, probably because the tissues cannot be sufficiently 

 depleted of their calcium. There is no reason to suppose that the para- 

 thyroid secretion, if there be such, is removed by this dialysis ; it is prob- 

 ably returned to the body in the perfused blood, so that its absence does 

 not produce the effect. To bring this result into relation with the con- 

 dition in parathyroid tetany, animals suffering from tetany were bled 

 and the blood was replaced in one case with normal blood, in the other 

 with dialyzed blood poor in calcium. The normal blood was found to 

 relieve tetany at once and to lower the peripheral excitability, while the 

 dialyzed blood did neither. "We, therefore, believe that this is further 

 proof that in the tetany of parathyroidectomy also the twitching and 

 Iiyperexcitability of the nerves is due to lack of calcium in the blood and 

 tissues." 



Uhlenhuth (It) tested the action of calcium and magnesium salts on 

 certain thymus fed salamander larvae showing tetany, and found that both 

 suppressed the muscular convulsions, but failed to prevent the other 

 symptoms of tetany. These, which he believes are due to lesions in the 

 central nervous system, caused by a specific poison produced by the 

 thymus, cannot be influenced by either calcium or magnesium. For the 

 most part, these lesions in the nervous system result in death, in spite 

 of calcium or magnesium administration, which affects only peripheral 

 excitability. Magnesium is more effective than calcium. 



Intoxication Theory of Parathyroid Tetany. Ammonia as the 

 Toxic Agent. As already stated, MacCallum and Voegtlin, in their 

 earlier experiments, found that the ammonia content of the blood of dogs 

 suffering from experimental parathyroid tetany was enormously in- 

 creased, sometimes reaching a value ten times as high as the normal. 

 There was an increased output of nitrogen and of ammonia in the urine, 

 and increased ammonia ratio also in the urine. 



Berkeley and Beebe (a) strongly incline to the idea of a metabolic 

 toxin as the cause of the symptoms, since bleeding without other measures 

 gives relief, and they consider, among others, ammonia and xanthin as the 

 possible toxic agents involved. They found that the muscular tremors 

 and contractions produced by both these substances, when given intra- 

 venously, were promptly relieved by calcium and strontium. They also 

 observe that in eclampsia and other conditions now believed to be related 

 to parathyroid tetany, large quantities of nitrogen and of ammonia are 

 often found in the urine. 



Jacobson (a) (11)10) injected ammonium salts into the veins of dogs 

 and cats in sufficient quantity to produce symptoms similar to those of 

 tetany. She then estimated the amount, and compared it with that pres- 



