36 1'IIYSIOLOGY CHAP. 



'Hi is may l>r because they throw into the circulation a secretion 

 that accelerates the renal elimination <>f the products of tissue 

 consumption; and these in all probability constitute the materia 

 peccans. The tetany consequent on parathyroidectomy is a neces- 

 sary consequence of the accumulation of katabolites owing to the 

 defective function of the parathyroids, and the therapeutic action 

 df parathyroid juice is the proof that the parathyroids contain 

 protective antitoxic substances. 



On this assumption it is easy to understand why parathyroid- 

 ectomy alone determines an acute auto-intoxication, and thyro- 

 parathyroidectomy a less acute auto-intoxication, which runs a 

 slower course. In the first case, where general metabolism is 

 active, owing to the presence of the thyroid, the amount of 

 toxic matters accumulating in the blood is larger ; in the second 

 it is, on the contrary, smaller, because metabolism is reduced 

 owing to absence of the thyroid. This is the reason why the 

 de-parathyroidised animal is attacked by morbid symptoms, when 

 subjected at a later period to thyroidectomy. 



In support of his views Vassale adduces the following experi- 

 mental data : 



(a) The phenomena of " tetania parathyreopriva " are more 

 serious in young than in very old animals. 



(&) The said phenomena are more acute and more rapidly fatal 

 to the animal, if it eats much, especially meat, after the operation. 



(c) Fasting reduces the pathological syndrome consequent on 

 thyro-para thyroidectomy. 



(d~) In animals deprived of the parathyroids alone, when 

 metabolism is normal, cicatrisation of the wound in the neck 

 occurs regularly by first intention ; in animals deprived of the 

 whole thyroid body it is on the contrary difficult in spite of 

 every antiseptic precaution - - to obtain healing of the wound 

 per primam, owing to the sluggish metabolism. 



In conclusion, we must add that, according to the latest 

 researches of Alquier and Theuveny (1907), and of Vassale's pupil 

 Massaglia (1908), the renal lesions which are, as we have seen, 

 inevitable on the extirpation of the entire thy ro- parathyroid 

 system, are in reality due solely to the suppression of the para- 

 thyroids, their secretion no longer being able to neutralise the 

 toxic products of metabolism, which therefore injure the renal 

 system, producing albuminuria and tetanic convulsions. 



The pathological anatomy of man confirms the experimental 

 data from other animals, i.e. it teaches us that the tetany of 

 thyroid excision, the so-called "tetania thyreopriva," is only a 

 "tetania parathyreopriva." We owe to Erdheini some careful notes 

 on serial sections of the organs of the neck in three persons who 

 died from tetany after excision of the thyroid. In two of these 

 the parathyroids were entirely wanting, in the third, one only 



