456 METABOLISM, NUTRITION, AND DIET 



tus is responsible for the derangement of functions noted. Only the symp- 

 toms safely ascribable to the thyroid proper have been presented above. 



Accessory Thyroids. Detached portions of thyroid tissue in the 

 neighborhood of the lateral lobes have the same structure as the thyroid 

 proper. 



The Parathyroids. There are smaller glandular structures associated 

 with the thyroids on each side known as the parathyroids. One is located 

 at the level of the lower border of the cricoid cartilage and in intimate rela- 

 tion to the posterior border of the lateral lobe of the thyroid. The other is 

 at the inferior border of the same lobe. In the dog there is an anterior para- 

 thyroid at the head of the thyroid and an external imbedded in the mass of 

 the thyroid. Extirpation of the parathyroids in the dog (Berkeley and Beebe) 

 leads to even a more profound disturbance of the metabolism resulting 

 in death. The usual symptoms are acute muscular weakness leading to 

 tetany followed by prolonged condition of increasing stupor and death. 

 Removal of the parathyroids in the dog leads to an increased excretion of 

 calcium and of ammonia and of other products indicative of disturbed met- 

 abolism. The derangement of calcium metabolism suggests the thought that 

 the symptoms might be relieved by supplying this substance. The matter is 

 presented in the following words of Berkeley and Beebe: '" Probably the 

 most striking argument in favor of Macallum's theory in respect to tetany 

 parathyreoprivus is that it may be relieved almost instantly by the intra- 

 venous injection of a soluble calcium salt. We have repeated the experi- 

 ment and find that intravenous injections of a soluble calcium salt will re- 

 lieve tetany almost instantly; intramuscular injections may be effective after 

 a period of thirty to forty-five minutes, and a similar period is required for 

 the beneficial effect after subcutaneous injection. The effect of the calcium 

 salt when given intravenously to an animal in advanced states of acute tetany 

 is one of the most striking in the range of physiological experimentation." 



Nucleoproteins are richly present in the parathyroids and their extracts. 

 Injections of nucleoprotein preparations freshly prepared also relieve the 

 symptoms of acute tetany in dogs. The above authors close their discussion 

 with the statement: "In other words, we believe that the essential fact in the 

 production of symptoms following complete thyroparathyroidectomy is the 

 deranged metabolism giving rise to some active poison, and not the abnormal 

 excretion of calcium which we regard as an accompanying phenomena, 

 perhaps due in part to the starvation cachexia which ensues in most cases if 

 the animal is tided over the acute condition." 



The Suprarenal Capsules or Adrenals. These are two flattened, 

 more or less triangular or cocked-hat shaped glandular bodies, resting by 

 their lower border upon the upper border of the kidneys. 



The gland tissue proper consists of an outside firmer cortical portion, and 

 an inside soft dark medullary portion, figure 312. 



