It was his work among the poor particularly that enabled Corrigan to recognize the differences between these two diseases. He came to have one of the largest practices that any practitioner in Dublin, or for that matter in any city of the world, has ever enjoyed, if enjoyment it can be called. His office used to be crowded with patients who would occupy all his time if he allowed them to do so. In order to secure opportunities for his other work, for his lectures, for his hospital visitation, and for his pathological investigation, he had a back entrance to his house through which he could steal out--even though there were many patients waiting for him--when he felt that it was time for him to fill another engagement. Late in life, after his return from Parliament when he took up his practice again, it was only a very short time {206} before the same state of affairs developed once more. It almost seemed as though every sick Irishman and Irish woman wanted to have the opinion of Dr. Corrigan. He had also a large consultant practice, though he was known for being a very different man from the ordinary type of the medical consultant. As one of his younger colleagues said, "he never wore the supreme air of a consultant." He was always simple and easy in his manner, was always congenial and ready to listen to what had developed and had been found in the case before consultation with him, and had none of that superciliousness that was supposed to characterize the true high-grade consultant physician in the British Isles a half a century ago. Within a few years after his essay on aortic heart disease, Corrigan published a paper on chronic pneumonia or, as he called it, cirrhosis of the lungs. Corrigan's successful achievements in medicine depended mainly on the fact that he studied the pathological anatomy of fatal cases with the greatest care. He had detected that in certain cases of chronic pneumonia the process seemed to be quite different from tuberculosis. Observations made postmortem showed that his clinical observations were justified by the differences observed in the organ. As a result he formulated his opinions on the subject. He called particular attention to the fact that what he found corresponded very closely with the pathological process which had been observed by Laennec in the liver, and to which the French medical pathologist had given the name of cirrhosis. It would seem as though the pathology of the time was so crude that Corrigan must surely fall into serious errors in his account of what he saw. Twenty years later, Virchow was to revolutionize pathology by the publication of his "Cellular Pathology." Notwithstanding the progress made since his time, {207} however, Corrigan's description of the condition of the lungs that he noted and of the pathological process observed is so true that even to the present day this paper remains of distinct value in medicine and represents the beginning of correct ideas on the subject.