This connection may result—
1st. From the presence of symptoms which resemble, or are identical with, those which we recognise as expressions of the physiological function of the sympathetic, and which we have enumerated and explained in the former part of this essay.
2ndly. From pathological anatomical changes in the sym pathetic nerve.
Those conditions usually go together, but not invariably; thus, the pathological alterations may be completely wanting, or, on the other hand, they may be found in cases which were not before suspected to have any connection with the sympa thetic system.
We begin with the consideration of the affections of the cervical sympathetic, afterwards taking up those which pro bably have relation to some change in the thoracic and abdominal portions of that nerve.