The question whether the functions of the lungs are more immediately connected with the influence derived from the ganglions, may be decided by the following facts. 1st, If on the one and the other side of the neck, the nervous thread be cut, which is usually regarded as the trunk of the great sympathetic, there follows little or no alteration in the phenomena of respiration. 2dly, If the par vagum and the great sympathetic be divided at the same time on both sides of the neck, the animal will die after a certain time, and much in the same way, as when only the par vagum is divided. 3dly, When we divide the sympathetic nerve in the neck, we do not deprive the lungs of the nerves which come from the first thoracic ganglion; now these nerves may contribute to keep up the action of the lungs, since, as I have said, each ganglion is a nervous centre, capable of emitting its own peculiar irradiations, independently of the other centres, with which it communicates. But whether the nerves, which are derived from the first thoracic ganglion, do really assist the functions of the lungs, I have not been able to ascertain by experiments on the nerves themselves, for such is the position of the first thoracic ganglion in most animals, that it cannot be taken away without doing so much injury to the parts as would kill the creature, or throw it into such agitation, as wholly to confound the phenomena of which we are in search, with those of a general distress and trouble. From analogy, however, and from the destruction of other ganglions, by which the internal organs are supplied, we should not have a right to suppose that the lungs would cease to act, when the ganglion in question is destroyed. Besides, the following reasons appear to me to prove unquestionably, the principle which I advance. If great lesions of the brain have the effect of suddenly interrupting respiration, because this organ can no longer influence the lungs by means of the nerves, which come from the first thoracic ganglion, it is evident that if all communication between the brain and this ganglion be taken away, such influence must cease, and respiration be suspended; but if we divide, as Cruikshanks has done, the spinal marrow on a level with the last of the cervical vertebræ, the animal will continue to live and breathe for a length of time, notwithstanding the want of communication between the brain and the lungs, by means of the first thoracic ganglion. From the above experiments, we may conclude, that the brain does not exercise any direct and actual influence over the lungs, and consequently that other causes must be sought for, if we mean to account for that sudden and instantaneous cessation of the functions of the latter of these organs, when those of the former are suspended.