fascinating path of nature, to be conducted along rather by the steady light which she may afford, than by those gleams or flashes with which art may attempt to beguile your imagination. I freely concede that one is a task, while the other is a pastime; that one involves the widest and a toilsome research, while the other is so purely a matter of sense as to admit of nothing else than an agreeable exercise of vision. Such of you as may prefer the former, will become enlightened physicians, will find in organic inquiries the best of your enjoyments, and will realize in yourselves what gives the highest value to man; but such as will be satisfied with the illusions of sense, as they abound in the outskirts of medicine, will become the victims of sense, and your patients the victims of error.

As you advance in the knowledge of Physiology, you will see that the effects of life are so various, and so obviously influenced by natural agents, and even by what is within-by the mind itself—you will necessarily conclude that the principle of life is also unlike all the other powers in nature in being endowed with certain properties, and liable to certain changes, which are totally unknown to the inorganic world. You will see, for example, that this principle is

variously acted upon-and according to the nature of the agents, and that motions and other effects ensue more or less in conformity with the influences which are exerted. These phenomena have given rise to an analysis of the principle of life; and practical uses as well as philosophy have ascribed to it a property of irritability, as well as of mobility;—just as they have to the soul the properties of judgment, reflection, &c. Mobility implies the power of acting, and is a very convenient name among those who are inclined to understand each other. Irritability has been long in use to denote a peevish mind, and by a little modification of its import in that relation, we shall find it a very convenient and useful term to denote the property in organic life upon which all things make their direct motory impression, and through which the moving power brings the mechanism into action.*

*See Author's Institutes of Medicine, § 177-215; 253267; 452-461, where this subject is extensively considered. Also, as related to the modifications of irritability in man and the different species of animals and plants, and through which certain morbific causes will induce disease in one species and in no others, and for physiological facts disproving the contagiousness of diseases which are known to be often produced by miasmata and other atmospheric agents, see, in connection, § 133— 152; 191; 652, 653. In respect to this mooted question, it is

So far, then, and much farther, all things are common to plants and animals; the whole assemblage of which constitutes their essential or organic life. But there are certain things peculiar

unimportant whether the well-established dependence of intermittent and yellow fevers, &c., upon miasmata or other atmospheric causes, or their assumed dependence upon admitted hypothetical "animalcula," or "fungi," be received; for it is just as absurd to suppose, (as imagined by some writers,) that the human organism can reproduce the animals or plants, (which is only a phase of spontaneous generation,) as to attribute to it the generation of those specific atmospheric agents which are commonly supposed to be the prevailing causes of yellow fever, intermittents, the malignant cholera, &c, in man, or another analogous cause to determine the "potato-rot," or another to produce an epidemic among horned cattle, or another among horses, according to the nature of the atmospheric poison and the exact nature of the plant or animal. So, on the other hand, if the virus of the smallpox, and of other contagious diseases, be generated by the living organism, it cannot be reproduced by chemical decompositions, and such diseases are, therefore, propagated alone by contagion. The facts and the philosophy are equally good in both the cases, and mutually sustain each other. But I would willingly waive the specific facts at the risk of those upon which the philosophy is founded, and thus rest the doctrine upon the immutable laws of organic life and as they are distinguished from those which govern the mere physical world. To the wavering upon this ques tion of contagiousness of cholera and yellow fever, especially, and to effect a substitution of a profitable attention to the cleanliness of cities for the useless system of quarantine, I may also introduce, in this place, a combination of laws which I formerly set forth as distinguishing those diseases which are truly communicable without contact from all other affections, namely, that they have never

to animals, and, therefore, as there is reason to believe, are totally wanting in plants. The latter, for example, neither see, nor hear, nor smell, and these are functions which many are apt to sup

been known to arise from any other source than human contagion; that they are distinguished by definite symptoms, a regular course of rise and decline, and actually terminate at a definite time which cannot be accelerated by art; and that they rarely affect us a second time. (See Author's Medical and Physiological Commentaries, Vol. 2, p. 507-514.)

In connection with the foregoing subject, I will not neglect saying that there are no speculatists in medicine so great as they who insist most strenuously upon nothing but facts. If proof of this be required, it may be found in the assumption of animalcula, and fungi, and ozone, as the causes of epidemics, and the specific treatment which proceeds upon those assumptions, not only to the neglect of the absolute pathology, but of the symptoms of disease; or an extensive survey of the subject may be seen in the Author's Institutes of Medicine, § 4—5; 349; and in the Article on the Writings of Louis, in the Medical and Physiological Commentaries, Vol. 2, p. 679-815.

Though not relative to my subject, I will embrace this opportunity to say that my views respecting the pathology and treatment of the malignant Cholera, as expressed in my Work upon that disease, remain without change; that I still regard the disease as a congestive fever, of which the collapse is the stage of universal invasion, or cold stage of fever, as is well understood by all who have been so fortunate as to witness the stage of reaction, and the subsequent slow progress of recovery,-that all the antecedent symptoms proceed from local derangements, and that the diarrhoea, therefore, is only a contingent symptom which commonly precedes the explosion of the constitutional malady, and is only so far on a par with many other symptoms which mark the ap

pose are the very essence of life. But this is a very false conclusion, for the animal would live just as well without eyes, nose, or ears. This is distinctly seen in the condition of the foetus, and

proach of other fevers, or as that same symptom, under a modified state of the abdominal secretions, often precedes an attack of typhus fever, and the pathological cause of which is very apt to become the immediate exciting cause of either of the general affections. The intestinal affection is not at all necessary to the malignant Cholera, nor is the suppression of urine. I have known the former to have been wholly absent, and in the East Indies, and among the negroes of the Mississippi, there have been a multitude of similar cases. That form is called, by physicians in Louisiana, the Cholera sicca! I have also known the urine to have been freely passed "in two cases during protracted collapse, and in which the patients were pulseless from the beginning, in the private practice of C. A. Lee, M. D." (Paine's Letters on the Cholera Asphyxia of New York, 1832, p. 117.) This has been common in Paris in 1849. The suppression of urine, however, is much more uniform than the absence of diari hoa, and hence some writers have supposed that the disease consists essentially in that symptoin, while a greater number regard the diarrhoea as the sine qua non. These unhappy views in pathology have engaged my attention in the Institutes of Medicine, where they may be found particularly under the articles Astringents, Antispasmodics, Diuretics, and Expectorants, by those who are interested in the inquiry. Also, in my Essay upon the Writings of M. Louis. Were the prostration of the circulatory organs, which is always present, assumed as the significant symptom, it would have some point as it respects the general pathological condition. The name of the disease has been an unfortunate one, having led to much of the error in respect to its pathology, and to a great deal in its treatment.