574 OSKAR KLOTZ 



9 



the dentine developing subsequent to the extirpation of the parathyroids 

 showed little or no calcification. This was found true not only for the 

 teeth, but also for bony structures. Fractures of bone occurring subse- 

 quent to the removal of the parathyroids failed to heal by osseous union 

 and showed a lack of calcification. Under these conditions, where the 

 animal survived a considerable period of time, the bony structures lost 

 some of their calcium salts, becoming more elastic and resembling bones 

 observed in osteomalacia. Bauer associates the presence of osteomalacia 

 in a human case with the presence of an adenoma of the parathyroid. 

 Fleischmann compares the results obtained in the experimental animals 

 with the somewhat similar changes observed in rickets.. In the human 

 cases there is not only a deficiency in the bone production and the process 

 of calcification, but a similar lack of calcium precipitation is found in the 

 teeth. Escherich suggested functional deficiency of the parathyroids and 

 congenital parathyroid hypoplasia as factors related to the occurrence of 

 rickets. This relation was assumed but not demonstrated, the assump- 

 tion being based on the frequent coincidence of tetany during the pro- 

 gressive stages of rickets. The suggestion found some support in the 

 evidence of calcium deficiency in the dentine of the molar teeth in experi- 

 mental animals in which the parathyroids had been removed (Erdheim, 

 Fleischmann). A study of four cases of rickets, by Schmorl, showed 

 no lesions in parathyroids. 



In 1906, Askanazy reported upon a case of osteitis deformans with- 

 out osteoid tissue, in which the left lobe of the thyroid was involved in a 

 tumor resembling a new growth arising from the parathyroid. Osteo- 

 malacia was not present. Subsequently, Schmorl examined four cases 

 of osteomalacia, and in only one of them found an adenomatous hyper- 

 plasia in the parathyroids. In the other three these glandules appeared 

 normal. Strada observed a hyperplasia and enlargement of the para- 

 thyroid in a case of osteomalacia, which was thoroughly studied. It is 

 interesting that in this group of cases, the hyperplasia of the thyroid was 

 associated with altered calcium metabolism leading to defective bony 

 development. 



The Parathyroids and Paralysis Agitans. In 1885, Horsley observed 

 that when the thyroid was completely removed, a remarkable train of 

 symptoms, beginning as slight fibrillation of the muscles of the hands and 

 feet and progressing to a constant tremor, made their appearance. These 

 tremors jx-rsisted until shortly before death. Horsley believed that these 

 observations were of importance, as tending to explain the causation of 

 the constant tremor seen in paralysis agitans. At the time of Horsley' s 

 work the existence of the parathyroids as functional entities was not 

 recognized, and it is probable that the thyroidectomy reported included 

 the removal of the parathyroids. Similar observations made by Lang- 

 hiins, and, subsequently, Berkeley and Lnndborg brought forward the 



