THE THYROID GLAND AND ITS DISEASES 209 



Dense perifollicular plexuses are also found enclosing the thyroid 

 follicles. Fine twigs from such a plexus terminate in little knob-like 

 swellings at the bases of the gland cells, the function of which has not 

 yet been definitely ascertained. Cannon and Cattell conclude, as a result 

 of their studies of the electromotive phenomena accompanying secretion, 

 that these terminals belong to secretory sympathetic fibers. Cannon, 

 Binger and Fitz, and Cannon and Fitz present additional evidence in 

 support of the same contention. They anastomosed the anterior root of 

 the phrenic with the cervical sympathetic trunk, and claimed that symp- 

 toms of hyperthyroidism were thus produced by the repeated stimulation 

 of the gland through the phrenic and sympathetic at each respiration. 

 The frequent association of lesions in the superior cervical sympathetic 

 ganglia with exophthalmic goiter, as described by Wilson and others, 

 is of interest also in this connection. 



Mott has, likewise, described chromatolytic changes in all the cells 

 of the central nervous system in hypothyroidism ; and Wiener observed 

 the atrophy of a lobe of the thyroid, and a decrease in thyroglobulin 

 on the side from which he had removed the inferior cervical ganglion 

 (citation from Schafer). Yet it is claimed that thyroid grafts are in 

 no way dependent upon nerve supply in order to produce secretion (Kum- 

 mer). 



From the anatomical point of view, these fibers terminating in con- 

 tact with the secreting cells may equally well be visceral sensory; but 

 we would hesitate to suggest that this is the correct interpretation. Visceral 

 sensory fibers for the thyroid gland do arise from the cells of the first 

 six cervical spinal ganglia, but their peripheral relations are unknown. 

 Very little reliance can be placed in isolated descriptions of nerve cells 

 occurring in the interfollicular connective tissue. There is no anatomical 

 evidence in favor of the existence of sympathetic reflexes, as postulated 

 by same authors. 



In addition to this sympathetic connection, fibers of the superior 

 and recurrent laryngeal nerves have been described entering the gland. 

 The recurrent nerves are thought to carry vasodilator fibers. Ossokin 

 has obtained evidence indicating that the inferior laryngeal and the 

 pharyngeal branches of the vagus both supply twigs to the gland. Ascher 

 concludes that secretory or excitoglandular fibers are contained in the 

 superior and inferior laryngeal nerves, but the criteria which he used for 

 secretory activity are not entirely satisfactory. Gley writes that "it has 

 been thought possible to prove directly the action of the nervous system 

 on the thyroid by showing that stimulation of the laryngeal nerves (L. 

 Ascher and M. Flack, 1910) increases the excitability of the depressor: 

 it being admitted, following the researches of E. de Cyon, that the latter is 

 dependent on the thyroid secretion." This dependence, however, is 

 denied by Schafer. The difficulty of maintaining functioning grafts of 



