THE RELATIONS BETWEEN THE EKDOCRIN ORGANS 173 



ture, absence of eosinophilia, no disturbance in respiratory rhythm, and 

 alimentary glycosuria. 



It has long been taught that the thyroid secretion, when in excess, 

 sensitizes the nerve cells, and particularly those of the vegetative system, 

 as shown by Cannon and his coworkers. We find a hyperirritability of the 

 same cells in states of psychic perturbation generally, and psychical dis- 

 turbance is more or less prominent in hyperthyroid cases. I cannot help 

 thinking that the psychical condition of the patient is responsible for many 

 of the clinical symptoms of the disease. In speculating as to the reason 

 why at one time the symptoms should be those of vagotonia, and at an- 

 other those of sympathicotonia, I would suggest that symptoms are prone 

 to appear on the part of that division of the vegetative system in which 

 the irritability of the cells is most marked. Aside from this, however, we 

 must not lose sight of the fact that there seems to be a mutual reaction of 

 the secretions from the suprarenal and thyroid. Since both of these secre- 

 tions are sympathicotropic, it may be inferred that the thyroid secretion 

 naturally has the greater affinity for the sympathetics. 



Changes in Sympathetic Ganglia in Graves' Disease. Another very 

 interesting relationship between the cervical sympathetics and the thyroid 

 is suggested by the studies of Jaboulay, Wilson and Durante, and Wilson, 

 in which histologic changes were found in the cervical sympathetic gan- 

 glia in hyperplastic toxic goiter. We can only speculate as to the relation- 

 ship between the condition in the gland and that in the thyroid. Does 

 one depend on the other ;. and which is prima'ry ? Stimulation of the 

 cervical ganglia can produce exophthalmos, rapid heart, and increased 

 activity on the part of the thyroid, so it seems that, if there is a causative 

 relationship, the gangliary changes probably stand as the cause. In this 

 connection, the experiment of Cannon, Binger, and Fitz, in which they 

 succeeded in producing exophthalmos, tachycardia, and increased body 

 metabolism in a cat by joining the phrenic nerve to the cut cervical sym- 

 pathetic, is of especial interest, 5 



The Autonomic System in Hypothyroid States, The relationship of 

 the thyroid secretion to the nervous system may be further studied in cases 

 of withdrawal of the substances, either experimentally, or, as we find it 

 clinically in cretinism and myxedema, or in the milder hypothyroid states. 



In these conditions certain inhibiting disturbances in the normal action 

 of the sympathetics is evident. The skin may be dry, the hair lusterless 

 with a tendency to premature grayness, the pulse slow, the circulation slug- 

 gish, and the metabolic rate reduced. The patients feel cold and actually 

 may have subnormal temperature. Injections of epinephrin may fail to 

 produce glycosuria and pilocarpin fail to produce sweating. 



The parasympathetics are also below the normal in excitability, but 



6 Langley, years ago, and several observers since have failed to secure successful 

 results in this experiment. R. G. H. 



