324 THE DUCTLESS GLANDS 



calcium theory is that simply bleeding the animal and then 

 replacing the blood shed by an equal amount of calcium free 

 isotonic solution of sodium chloride (thus still further diminish- 

 ing the calcium content of the tissues) also brings about prompt 

 relief. 



Various toxic agents have been suggested as being responsible 

 for the phenomena of tetany. Among these are ammonia, 

 xanthin, histamine, thymus secretion, inosinic acid, guanidine, 

 and methyl guanidine. The only substance in this list which 

 need be seriously considered is guanidine. In 1912, W. F. 

 Koch made the very important discovery that methyl-guanidine 

 is constantly present in considerable amount in the urine of 

 parathyroidectomized dogs. In 1913 he definitely attempted 

 to correlate this observation with the function of the parathy- 

 roid glands. He suggests that the parathyroid secretion is 

 concerned with anabolic processes closely related with the 

 building up of nucleins. This hypothesis has been developed 

 more fully by Paton and his co-workers. They claim that 

 guanidine injected into an animal will produce all the symptoms 

 of tetany. They attribute this condition as found experi- 

 mentally or clinically to an abnormal accumulation of guanidine 

 in the body, which accumulation it is the duty of the parathy- 

 roid to prevent. 



It has been supposed that the thymus produces a toxin 

 tending to give rise to tetany, and that it is the duty of the 

 parathyroid to reduce or destroy this. 



The parathyroids do not contain any measurable amount of 

 iodine. Other than this there is nothing to be said on the 

 subject of the chemistry of the glandules. Attempts have been 

 made to isolate the " active principle," but so far no very 

 definite results have been obtained. 



