sincere wish and desire, I may almost say command, (for in such matters the child may command the parent,) that you will often remind me in your letters of the temptations to which I am exposed, and the incentives to avoid them. Do not think that I am writing words which mean nothing. It had been my attention for some weeks past to write to you, before I left the country, on this very subject; to request your direct and constant aid in the preservation and improvement of my moral character. I hope that you will read and understand this request literally; as much so as any I ever made for a book to improve my mind, or a dollar to clothe my body. One duty yet remains, a cheerful and a pleasant one and yet one which I can perform but too inadequately; - it is to express my gratitude to you; to express to you all that I feel would be impossible; -- perhaps also it would be unnecessary, as you must know it already. It might have been expressed more fully, and most becomingly in the actions of my past life; but it has not been. No mode is now left me, but by words and my future conduct. No words that I can use, can ever exhibit to you my real feelings; and for my future conduct I fear, yet hope. The duties of a parent to his child, which your approving conscience must tell you in more audible tones than I can utter, have been by you most strictly exercised, call for a correspondent gratitude from the child, none the less because they are the duties of his parent. But in my case, there is something more than this. Though I love to dwell upon the relation, which exists between us, and the circumstances, and scenes, and events, which have arisen from that relation; yet I have sometimes taken another view of the subject. I have considered the relation of parent and child as adventitious or accidental; I have looked upon you and myself as two beings whom God has placed upon this earth, and whom accident had brought together; I have then thought of how much I was indebted to you for all the principles, and knowledge, and powers that I pos- but, my dear father, I will stop. You see what is in my mind, I have been writing you, till I am getting too much excited; but it is a holy excitement and will do me good. My prayer is to God, that we may meet again in this world, but I know it is uncertain; my prayer and efforts too are and shall be, that my life may be so spent as to meet you in another world, if not in this, which may God in his infinite mercy grant.' - pp. 11-17.

sess;

These letters require no comment. They speak directly to the heart of every parent and child.

The subject of this Memoir was excited to greater ardor, if that were possible, in his professional studies by the new means of improvement afforded him at Paris, and the new views of

the science of medicine which opened upon him. He particularly attached himself to the instructions of M. Andral and M. Louis. By both he was treated with great attention and kindness; and between M. Louis and himself there " grew up a friendship of no common kind;" as is evidenced by the letters of M. Louis as well as his own, published in this vol

ume.

That gentleman has gained a distinguished name by his new method of observing the phenomena and studying the causes of disease; and as Dr. Jackson jr. entered with zeal into his views, and promised to be among his most eminent disciples, we quote the following passages from an account of this new method given in a note to the Memoir.

"M. Louis has not brought forward a new system of medicine ; he has only proposed and pursued a new method in prosecuting the study of medicine. This is nothing else than the method of induction, the method of Bacon, so much vaunted and yet so little regarded. But, if so, where is the novelty? If any one, after patiently studying and practising the method proposed by M. Louis, denies the novelty of it, I will not dispute with him a moment. Perhaps he will then agree with me, that it is a novelty to pursue the method of Bacon thoroughly and truly in the study of medicine; though it is not new to talk of it and to laud it.

"A little history of one part of M. Louis's life will throw some light on this subject. This gentleman went abroad, and I believe had some appointment in Russia, after he had gone through the usual course of professional education. Returning to France at the age of thirty-two, he was about to engage in private practice. He was then led to examine anew the state of the science of medicine, and was dissatisfied with it. He now decided to abandon the thoughts of practice for a time, and to devote himself to observation; that is, to the study of disease as it actually presents itself. With this view he went into the hospital la Charité in Paris, and followed the practice of M. Chomel, now a physician at the Hotel Dieu and Professor of Clinical Medicine, and highly esteemed as an author. M. Louis passed nearly seven years in studying medicine in this way. The first part of this time he was learning how to make observations. When he thought he had attained this art, he threw away, as I have understood, the notes he had already collected, and began anew to accumulate exact observations of the phenomena presented by the sick, and of those derived from an examination after death in the fatal cases. In this course of observations he did not make a selection of cases, but took them as they were presented, indiscriminately. He was not in a hurry to

make deductions from his cases, satisfied that he was gathering the materials, from which truth would ultimately be elicited. He was only careful that his observations should be correct, and had not any general principles or doctrines, for which he sought support or confirmation.

"To estimate the value of his observations, it is necessary to understand the plan on which he collected them. First, then, he ascertained when the patient under his examination began to be diseased. Not satisfied with vague answers, he went back to the period, when the patient enjoyed his usual health; and he also endeavoured to learn, whether that usual health had been firm, or in any respect infirm. He noted also the age, occupation, residence, and manner of living of the patient; likewise any accidents which' occurred, and which might have influenced the disease then affecting him. He ascertained also, as much as possible, the diseases which had occurred in the family of his patient. Secondly, he inquired into the present disease, ascertaining not only what symptoms had marked its commencement, but those which had been subsequently developed, and the order of their occurrence; and recording those which might not seem to be connected with the 'principal disease, as well as those which were so connected; also, measuring the degree or violence of each symptom, with as much accuracy as the case would admit. Thirdly, he noted the actual phenomena present at his examination, depending for this not only on the statement of the patient, but on his own senses, his eyes, his ears, and his hands. Under this and the preceding head, he was not satisfied with noting the functions in which the patient complained of disorder, but examined carefully as to all the functions, recording their state as being healthy or otherwise, and even noticing the absence of symptoms, which might bear on the diagnosis. Thus all secondary diseases, and those which accidentally coexisted with the principal malady, were brought under his view. Fourthly, he continued to watch his patient from day to day, carefully recording all the changes which occurred in him, till his restoration to health or his decease. Fifthly, in the fatal cases he exercised the same scrupulous care in examining the dead, as he had in regard to the living subject. Prepared by a minute acquaintance with anatomy, and familiar with the changes wrought by disease, he looked not only at the parts where the principal disorder was manifested, but at all the organs. His notes did not state opinions, but facts. He recorded, in regard to each part which was not quite healthy in its appearance, the changes in color, consistence, firmness, thickness, &c.; not contenting himself with saying, that a part was inflamed, or was cancerous, or with the use of any general but indefinite terms."

"It was only when he had accumulated a great mass of cases, that M. Louis began to deduce from them any general principles. He then arranged the facts he had collected in a tabular form, so as to faciltate a comparison of them. How much labor this required will be in some measure conceived, when I state that, while going through one class of his observations, those, I believe, which relate to acute diseases, he retired to a distance from Paris, and occupied ten months in making out his tables. This statement is, I believe, substantially if not precisely correct.

"Let the reader conceive of these tables, drawn out with accuracy, having columns devoted, with proper discrimination, to each function and to its various derangements, as manifested during life, and to each organ and its lesions, as ascertained after death; let him then go to these tables and inquire, under what circumstances certain signs of disease arise, and with what pathological changes in the dead body they are found to correspond; let him ask, under what circumstances certain morbid changes of structure occur, and with what symptoms they are found to be connected; he may find the answers, and he may obtain them numerically." pp. 59-63.

These general statements are further illustrated in the note; and examples are given of the facts that have been established by this more accurate and philosophical mode of observation. It seemed proper to give some account of it, as Dr. Jackson, jr., without doubt, did much, in the circle in this country with which he was immediately connected, to direct the attention of other physicians to the subject. M. Louis wrote to his father, urging that he should be allowed to devote some years after his return to Boston merely to "medical observation." His letter is given, together with the answer of Dr. Jackson, sen'r., assigning his reasons for not assenting to the proposal.

While the subject of this Memoir was residing at Paris, the irruption of the cholera into that city afforded a new opportunity for the exhibition for his moral and intellectual character. The heroism, sometimes demanded of the medical profession, that leads one calmly to expose himself to death, under the action of no false stimulants, to save, not destroy, the lives of others, is of a far higher character than that ordinarily displayed on the field of battle.

"The period of the epidemic cholera in Paris was one of the greatest interest and of the greatest anxiety to the subject of this

memoir. Until the end of the winter 1831-2, the accounts which we had received in this country of the cholera in Europe, were of the most alarming character. We knew that, arising many years previously in the hot climates of Asia, this deadly malady had passed in a north-west direction into the coldest regions of Europe, aud was thence extending itself over that quarter of the globe. Why it thus spread, and whether it was propagated by contagion, many persons were ready to decide upon general principles; but precise facts, on which to form a decision, were not yet furnished. One thing was certain, that it affected great numbers wherever it went, and proved fatal to a large proportion of those affected. Regarding my son as comparatively without friends in a foreign country, not then knowing the kind feelings already entertained for him by those most capable of taking care of him, I wrote to him urgently, to fly before this plague, and even to leave Europe, should the disease invade at once France and Great Britain. Such letters, and such only, had he received on this subject, when the disease appeared in Paris, in the last days of March. It had already been introduced into England, but had there been comparatively limited in its extension. In Paris, it extended at once to very large numbers, and assumed within one week the most terrific aspect; such as to excite within that short period the most outrageous mobs, under a belief that the poorer classes had been designedly poisoned. On the sudden outbreak of this most alarming disease, my son's mind was exercised in the most distressing manner. The following extract from his letter of April 8th, which will be given in full among his letters, will describe his feelings, and give the result to which he was brought in this dilemma.

"I almost weep to write you again from Paris. It is now the first moment of my life, that I have heen placed between two duties, each strong, each binding, and where my difficulty is to deIcide which is the most so. But I have decided, as I know, against your wishes. God grant that circumstances may be such that you shall accord with me, when the time is passed. A medical man has his duties; — I am a boy in medicine; granted. But I am like the other Americans here about me. An opportunity is offered us of studying a disease, which will probably visit our hitherto untouched country. Were the disease about you, would you fly? You could not, for the public would look to you. You would not, for your sense of duty would prevent you. I am, in a measure, in the same condition.'

"The moment was a fearful one, most assuredly. The mortality in Paris rose to eight hundred a day, within three weeks from the first appearance of the disease. It was in the Hôtel Dieu my son first saw the victims of it in any number, and the emphatic words in which he described it were nearly the same, as were often used