Before I begin to describe the parts which form the subject of this communication, and to show how some of them are merely modified portions or developments of others that belong to the medulla oblongata , it will be advisable to recur to those morphological changes in the medulla, which I formerly pointed out as themselves arising from modifications of the spinal cord . And while in unravelling structures so extremely complex, such a course seems almost necessary to facilitate their comprehension, and convey to the reader a just notion of their morphological changes, in relation on the one hand, to the remaining parts of the encephalon, and on the other hand, to the spinal cord, it will afford me an opportunity of adding to this recapitulation some new facts that have been elicited by subsequent observation and a more extended experience. It is gratifying to know that many of the results of my previous researches have been found to throw considerable light on certain diseases of the nervous system, especially on some forms of paralysis; and my own pathological investigations, as well as a close study of nervous disorders, have not only enabled me to shape my present researches as much as possible in accordance with the requirements of the pathologist, but, by pointing to the probability of certain anatomical connexions suggested by morbid symptoms, they have sometimes been the means of directing the course of my dissections in a very peculiar way.