THE PAKATHYROID GLANDS 517 



Capobianco and Mazzioti (1899) found that removal of all parathy- 

 roids is invariably fatal. 



Welsh (a) (1898) carried out a series of partial and complete re- 

 movals of the parathyroid* in the cat, and found that acute and severe 

 symptoms followed, although the thyroid remained practically intact. 

 With only one of the glands left in some cases, the animal was unable to 

 survive. He sa.w no evidence of the transformation of parathyroid into 

 thyroid tissue, and considered that there is no functional relationship be- 

 tween the two. 



Pineles (a) (1904) reported that in the monkey the symptoms are, as a 

 rule, more chronic than in the cat or rabbit. In his experiments the para- 

 . thyroids were taken away in two or three stages ; nothing happened until 

 the last glandule was removed, when death by tetany resulted. The loss 

 of three parathyroids, as a rule, gave rise to no acute symptoms. In his 

 cats, from which all parathyroid tissue had been removed, the average dura- 

 tion of life was five and a half days. As the result of his own experiments, 

 Pineles concluded that the acute tetanic symptoms and early death are due 

 to loss of the parathyroid glands, while the .chronic changes and trophic 

 disturbances arise from thyroid deficiency. 



Doyon and Jouty claim to have produced fatal results by removing all 

 the parathyroids in birds. The writer has attempted to extirpate the thy- 

 roids and parathyroids in chickens, and found the operation so difficult 

 that he was compelled to abandon the attempt. Doyon and Kareff obtained 

 similar results in the turtle. 



Erdheim (e) (1911) did some very careful work on the rat. This ani- 

 mal is said to possess only two (both external) parathyroids. In twenty- 

 nine animals, both glands were destroyed by a fine electrocautery and in 

 twenty-seven of these tetany appeared in from three to seven days. If only 

 the half of one parathyroid was left, either no effect at all followed or only 

 very mild symptoms, and in some cases slight indications of tetany were 

 seen after the removal of a single gland. In eight rats, a part of the 

 thyroid was removed without injury to the parathyroids, and in those 

 cases no signs of either acute or chronic symptoms appeared. Erdheim 

 believed that trophic symptoms may result from partial loss of the para- 

 thyroids. It is important to note that he made serial sections of all the 

 neck organs post mortem, and proved conclusively that whenever the para- 

 thyroids were entirely absent, no matter whether the thyroid was present 

 or not, the animal showed acute tetany. Usually symptoms appeared with- 

 in the first twenty-four or thirty-six hours, and these consisted of muscular 

 tremors and disturbances of various kinds, ending often in the status 

 epilepticus. It is interesting to compare this result with that of Vincent 

 and Jolly, who state that a the thyroids and parathyroids may be destroyed 

 or removed without affecting the animal (rat) in any way." It is within' 

 the limits of possibility that both statements may be correct. Much de- 



