lieved, but showing distinct tendency to return for many weeks afterwards. The recurrence of fits of coughing at one or more stated times each day was a very frequent symptom succeeding to these singular epidemics. I have recently seen a case of this kind, where a single paroxysm of coughing like the hooping cough occurred at a particular hour in the morning, for two or three weeks in succession; and at no other time during the day. Another instance is known to me, on good authority, in which the patient was affected by urgent thirst at a regular hour on alternate days, without other obvious symptom of disorder. Here also the character of the case was attested, not only by the periods of intermission, but by speedy cure under the use of the quina, when other means had failed. It is known that epistaxis sometimes occurs with the same regularity of interval, and is obviated chiefly by the employment of the same means. * Other instances occur, yet more obscure in kind, where there is seeming tendency to the recurrence of the same * Dr. Leonhard, of Muhlheim, relates a singular case of a woman in whom an attack of influenza (the severe epidemic of February and March 1837) passed into a local quotidian intermittent, affecting first the left, afterwards the right arm, with every successive symptom of regular ague; the rigour, heat, and stage of perspiration all distinctly marked in each fit other parts of the body wholly unaffected—the disorder cured by quinine. The most remarkable statement connected with the case is, that the pulse in the affected arm gave 90 beats, that of the other arm only 80, at the same moment of time. - We still indeed only partially recognise the many varieties which occur in intermittent fevers. Mr. Oldfield, who went up the Quorra in a steam vessel with Lander, describes with much exactness a quotidian which affected him in this river voyage; the paroxysm coming on at first about noon; then half an hour later every day, till it reached six o'clock; at this time an entire intermission of two or three days, recommencing afterwards at noon. This order was so often repeated that he could anticipate the daily time within a minute or two. symptoms, in the same order, after the lapse of several days. In such cases, collapse in one degree or other may generally be noted as a symptom; thereby connecting them in some sort with the aspects of intermittent fever, but under a more anomalous form. Examples of this kind, not always noted in their right connexion, though familiar to the observant practitioner, make it certain that there is a common principle pervading these intermittent disorders of regular type; the development of which forms an important object of future research. The translation of one form and seat of malady into another, and the subjection of all to well defined laws of time and order of occurrence (admitting, however, of certain familiar exceptions and anomalies) render this question one of the most interesting in pathology. Whether we may ever surmount the difficulties encumbering it is yet uncertain; though the prospect is better perhaps now than at any former period in medical history.* One path of inquiry as to all intermittent disorders of febrile kind, is that which directs towards the diurnal changes in the bodily functions, as well in the healthy state as under disease: a fact seemingly common to all animal life, but becoming more marked and characteristic in descending the scale of existence. In man the tendency of various disorders to exacerbation or remission at stated hours, affords remark * The late Dr. Maculloch, in his work on remittent and intermittent diseases, has dealt with this subject more explicitly than any other writer; and in assuming a single generic disease, the product of malaria as a specific virus, has associated with it many neuralgic and other affections, sciatica, headach, tic douloureux, toothach, ophthalmia, palsy, &c. Though the generalisation is obviously far too extensive, yet it marks throughout the acuteness of this author; and in connecting neuralgia generically with intermittent fever, offers something of more plausible arrangement for the curious facts noted above. able evidence of such natural changes within the daily period, distinct from the more obvious effects produced by sleep. Even the last great change, that of death, is observed often to happen at a certain time of the day, at which on preceding days there has been a collapse approaching to it. It is not easy indeed to obtain unequivocal evidence on this subject, seeing the great diversity as to time at which these periods of morbid action occur, even in the same specific disorder; and every interpretation is made more difficult by the disturbing influence of digestion in its several stages, and by the many other contingent habits of life equally affecting these phenomena. Nevertheless averages have been obtained, sufficiently free from error, to show that the functions of respiration and circulation do undergo certain determinate changes within the day; such as can scarcely exist without influencing the period and course of morbid actions, when these are in existence in the system.* Such natural diurnal * Dr. Prout has found that more carbonic acid is formed in respiration from daybreak to noon, less during the remainder of the twenty-four hours. Something of periodical change in other functions must needfully be produced by this difference, on whatsoever cause it depend. Observations on the pulse seem to show that there is an average acceleration of the motions of the heart in the morning, and retardation in the evening, independently of all causes of external influence; and greater excitability of the heart by stimulus, whether of exercise or food, at the former period than the latter. The recent researches of Dr. Knox upon this subject (Edinburgh Med. Journal, April, 1837) are very valuable; as are those of Dr. Guy, related in vol. vi. of Guy's Hospital Reports. These changes in the action of the heart, depending, it may be, on prior changes in the nervous system from sleep or other cause, have probably some effect on all functions of the body; but whether they are adequate to explain any periods of morbid action is very doubtful. The electricity of the atmosphere appears to undergo diurnal changes; the positive electricity being stronger during the day than in the night, with subordinate increments and decrements also during the day. The influence of these may not be great, but some effect they must have, and we have not means to appreciate its amount. changes, inexplicable on any known principle, may depend on periodical alterations in the nervous power, of which sleep is the chief index and example. But be it so or otherwise, the main question yet occurs, whether they are sufficient to explain the tendency in certain diseases to definite periods of one or more days, and the fluctuations from one type and time to another. It must be admitted in the present state of our knowledge that they are not so. Even were a plausible connexion thus established for the phenomena of the quotidian type, this alleged relation would render more difficult the theory of the others. The absence of the series of symptoms on one day becomes as difficult to explain as their presence on another; and the various subordinate types which have been described by medical authors serve rather to perplex than illustrate the question. No adequate explanation then has yet been drawn from this source; and the suggestion is merely one which seemingly leads us further than any other in an inquiry where hitherto so little has been attained.* * If venturing to name any particular periods in the twenty-four hours at which changes most obviously take place, both in health and disease, I should be led, on experience, to refer to the hours of two or three in the afternoon, and the corresponding time in the night. Such statement, however, has little value, seeing its vagueness, and the numerous exceptions to it which arise on every side. The individualities of each disease produce perplexity here; and, equally so, all peculiarities of temperament and habit of life. Every variation of diet, and each particular stage of digestion, have their appropriate effect on the other functions, even on those apparently the most remote. In adverting to the causes, whatever they be, which give an aspect of daily periodicity to some of the bodily functions, the proofs may be admitted that they have influence on the mind also; chiefly as respects the aptitude for exertion of its intellectual faculties, but partly even in relation to the character and intensity of the feelings. The physician, as well as common observer, have frequent opportunities of noticing this. The best evidence, however, is that which the cautious and candid observation of each person may furnish to himself. AA The existence of natural periods in the human constitution, more extended than the diurnal type, has been a favourite speculation with some authors; and undoubtedly the function of menstruation in all its parts furnishes justification of the doctrine, as well as some basis for the manner of treating it. Opinions or examples might be numerously quoted from different writers, in suggestion of periods of alternate days-of three days of three months of a year-not to mention those longer periods, which have been classed as distinct epochs or ages of life. But the evidence in most of these cases is that derived from morbid phenomena themselves, and in strict reason therefore it affords no explanation of disease from natural changes of corresponding interval or date. The acknowledgment in fact is needful that, with the exception of the various disorders depending upon or subordinate to menstruation, we have no authentic proof of such relations, though reason sufficient in the curious and intricate nature of the phenomena for diligent research through every channel that may be open to us. The influence of certain medicines, and particularly of bark, in curing even the most anomalous varieties of these intermittent disorders, is a fact of great interest. Like the use of mercury in obscure syphilitic affections, or of colchicum in the most irregular forms of gout, it enables us to denote and class together symptoms apparently the most remote in kind; but which presumably could not be thus relieved unless depending on some common morbid cause. We have therefore, in the specific nature of the remedy, a sort of practical test of the character of the disease; often of great importance to the consistency and success of our treatment; and related, through the principle of inquiry, to some of the most interesting questions in all pathology. This it is, as was noticed when speaking elsewhere of colchicum, which gives peculiar |