THE PAKATHYROID GLANDS 511 



nervous symptoms within the first week after the operation. Only one re- 

 mained alive at the end of the fourth week, and this single survivor suc- 

 cumbed in fifty days. Schiff also found that if, previous to removing the 

 thyroid, he transplanted into the peritoneal cavity the thyroid gland of 

 another animal of the same species, no symptoms followed. 



These experiments of Schiff mark the beginning of the scientific study 

 of the functions of the thyroid and parathyroid glands, and it is only since 

 the time of these observations that any real advance has been made. 



The observations of Schiff were confirmed by Wagner (1884), who 

 studied the nervous and muscular disturbances in cats particularly, and is 

 stated to have been the first to report an increase in the excitability of the 

 peripheral nerves to the galvanic current. Colzi (1884) and Sanquirico 

 and Canalis (1884) also reported similar results. 



Horsley (a) in 1885 described the nervous symptoms as they appeared 

 in dogs and, more particularly, in monkeys, which he was the first to em- 

 ploy in this work. According to his account, the monkey, as a. rule, appears 

 perfectly well for about five days after complete removal of the thyroid. 

 Then there is noticed a slight fibrillation of the intrinsic muscles of the 

 hands, feet, and jaws, following this order in successive invasion. As a 

 rule, the fibrillation soon becomes a constant tremor, to which is then 

 added a series of powerful clonic spasms. This paroxysmal stage usually 

 appears about the second or third day after the tremors are first noted and 

 persists for about twenty days. The spasms gradually fail in force, re- 

 assume the type seen at their onset and disappear, sometimes as long as 

 ten days before death. These nervous symptoms were less severe in the 

 monkey than in the dog. 



In 1891 Horsley (e), summing up the results of his work begun several 

 years before, divides animals into four classes as regards the results which 

 follow complete thyroidectomy. According to this classification, birds and 

 rodents show no ill effects. In the ungulates sheep, goat, donkey, pig the 

 symptoms develop very slowly ; there is a general cachexia, which finally, 

 after many months, results in death. In the third class, in which he places 

 man and the monkey, the effects are more severe ; myxedema is a marked 

 feature, with increasing cachexia, which ends in death. In the carnivora 

 removal of the gland is followed, in a few days, by acute nervous symptoms, 

 characterized by severe tetany and convulsions, with an early termination. 

 These results appeared to point to the conclusion that the food habits of 

 the animal have much to do with the effects which follow thyroidectomy. 

 The purely carnivorous animals, such as the dog and fox, are most severely 

 affected, the herbivora scarcely at all; while the omnivora, living on a 

 mixed flesh and vegetable diet, occupy a middle position. 



The observations of Breisacher, who found that dogs which were fed 

 on meat before and after thyroidectomy suffered more severely and suc- 

 cumbed sooner than those fed on milk, seemed to support Horsley' s conclu- 



