an irritant in the nose, pointed out a fact that had been forgotten or the significance of which had not been appreciated. The membrane of the nose concerned in smell is supplied by the first pair of cranial nerves, the so-called olfactory nerves. Between this olfactory nerve and the nerve which supplies the diaphragm, the phrenic nerve, which is a cervical and not a cranial nerve, that is to say, comes from the central nervous system through the spinal cord in the neck and not directly from the brain, the older anatomists declared there was no connection. Morgagni pointed out that the mucous membrane of the nose is partly supplied also from the fifth pair of cranial nerves. From the fifth nerve, small branches of connection with the cervical nerves, as low even as the intercostal nerves, had been traced by Meckel. This shows the possibility of a nervous reflex; that is, of a communication of nerve impulses without the necessity for the intervention of the central nervous system.

This was the first direct tracing of distant reflex nervous action in human physiology. The problem of nervous reflexes was to remain obscure for more than a century later, until light was thrown upon it by the investigation of the French physiologist, Claude Bernard. Here, however, was {43} the pregnant suggestion of the explanation of the seeming mystery. In subsequent cases Morgagni looked for the confirmation of his theory in this matter and found it. He pointed out that there was a relationship between the abdominal viscera and the olfactory mucous membrane of the nose. In one of his cases an epileptic seizure was always accompanied by a sense of discomfort in the upper abdominal region and a fetid odor. This odor was entirely subjective; that is, though extremely annoying to the patient it could not be noticed by any one else, even though the patient was close at hand and exhaled his breath at the moment of the observation.

This would seem to point to the fact that Morgagni suspected there were other connections between the special senses and important organs besides those which had been discovered by anatomists up to that time. As a matter of fact the so-called sympathetic nervous system does place all the organs of special sense in direct connection with the other important organs of the body. Morgagni's suspicions were to be confirmed by the discoveries made in this sympathetic system during the succeeding century.

Morgagni first of all seems to have realized what was the mechanism by which alcohol injures the human system. He pointed out that the excitation of the heart due to the action of alcohol was reflected in an overdistention of the arteries. This overdistention gradually led to degenerations in the arterial walls. The loss of elasticity thus induced brought on a disturbance of the circulation in the important organs of the body, and so gave rise to symptoms of wide-spread interference with organic functions.

Morgagni's studies in aneurism, that is, in the dilatation of bloodvessels, show how thoroughly he understood the mechanism of the formation of this serious pathological {44} condition. He pointed out that the first noticeable disease change that occurs is a degeneration of the inner coat of the artery. This leads to the formation of furrows on the inner wall of the vessels and finally brings on weakness of the middle coat of the artery. He realized that the progress of these arterial changes is due to a large extent to blood pressure within the arteries. He felt, too, that blood pressure could be kept from being dangerously high by strict attention to diet limitation. If aneurisms are discovered in early stages the patient's life may well be prolonged by these simple measures. This idea contains the germ of the Tufnell treatment, which has been the most successful therapeutic measure for the treatment of aneurism in the nineteenth century.

The Italian anatomist's acumen led him to appreciate better than ever before in medical history the influence of the mind on the circulation. He pointed out that emotions have a powerful influence on the circulatory system in all its parts. How much the peripheral bloodvessels are affected can be seen in the tendency to blushing during certain forms of excitement, involving shame or embarrassment; on the contrary, pallor in anger, or indignation, or fright. He pointed out, too, that the heart is affected by such emotions and is sometimes strenuously excited and sometimes very much retarded. Morgagni understood that the influence of such emotions in especially excitable individuals leads to wear and tear on the bloodvessels and so to a shortening of lives. He thought of some aneurisms, even those affecting the large bloodvessels, might be caused by sudden intense emotions, and especially by violent efforts to suppress or conceal emotions. We know now, however, that these pathological conditions are due to human passions, but quite other than those which Morgagni had in mind.

It is interesting to note that comparative {45} pathology--that is, the study of the diseases of animals as illustrating corresponding conditions in human beings--had already attracted the attention of the Bolognese school of medicine. Albertini, who had been a professor of Morgagni's, pointed out that aneurisms are rarely found in animals, because brutes were not subject to emotions as are human beings. Morgagni made still further observations in this line to confirm his own conclusions in the matter. For a time in his earlier life he devoted himself to the study of fishes, because they seemed to promise to throw light on certain problems in human anatomy and pathology.

How closely he studied pathological changes in tissues can be gathered from the fact that his observations led him to point out that aneurism of the aorta occurs most frequently at that part of the curvature of the aorta against which blood is constantly projected by the heart. The realization of the importance of this mechanical factor in the production of aneurism is one of the first successful results of carefully applied observation and knowledge of physical laws in the causation of changes in the tissues as opposed to elaborate theories with very little foundation in fact.

Variations in the pulse attracted his attention, and he was among the first to point out that the occurrence of flatulency is liable to cause disturbance of the heart's action and to bring on noticeable cardiac palpitation in the absence of any organic affection of the heart itself. Morgagni also pointed out that intermittence of the pulse may be due to nervous conditions. He showed that severe mental shock or trying emotions may cause irregularity of the heart's action and pulse intermittency. Some of his observations in this matter show an intuition with regard to the nerve supply of the heart that is quite beyond the anatomy of his time, and seems to indicate that he suspected the existence and {46} function of the sympathetic system and also the existence of a special nerve supply to the small arteries.

Perhaps Morgagni's most penetrating evidence of insight in pathology and its relations to clinical medicine is with regard to tuberculosis. Over a century and a half ago he insisted on its contagiousness. He refused to make autopsies on patients who had died of tuberculosis, and his position in the matter was undoubtedly of the greatest service in directing the attention of his contemporaries, and especially those closely in contact with him, to the important question of intimate association with tuberculous patients as a potent factor in the acquirement of the disease, more potent even than heredity which then occupied all men's minds on this subject.

It might be deemed that this advanced position of Morgagni was due rather to intuitive abhorrence of the disease than to the conviction of actual observation, and that his conclusions were the result more of prejudice than of real knowledge. Any such opinion, however, is absolutely contradicted by the