CHAPTER V. DURATION OF PHTHISIS. V. Prognosis THE basis of all prognostic calculations regarding CHAP. cases of consumption, must be founded on a knowledge of the actual average duration of the disease. And yet founded on there is no knowledge so difficult to obtain, and there duration. is no class of facts on which so great a variety of opinions has been offered. The causes of this divergence will be found, on investigation, to be referable to several heads. The different varieties of the disease itself, and its modifications by the various agents referred to in this work, stand at the head of these. So long as phthisis continues to be viewed as a single affection of invariable progress and termination, will contradictory opinions be offered as to its average duration. It is only by studying its natural divisions and assigning to each its separate and appropriate place, that we can hope to arrive at an accurate estimate of its length. Were a calculation of the duration of fevers to be inade from records including the exanthemata as well as typhoid, the intermittents and remittents, it is obvious that no records of accuracy or value for practical purposes could be deduced from such a method. We should reject such a classification, as unscientific and useless. Tuberculosis possesses, in the single fact of a certain amount of uniformity of the morbid material, a basis which includes all its subdivisions, but such wide deviations occur in its progress and results, that no average which should be CHAP. 6 of the slightest use in practice could be derived from the most careful records of all the instances of the disease which ever occurred under observation, were they viewed as a single affection. It is plain, that from so loose an opinion as Portal's, that the disease lasts from eleven days to forty years,' we can gather no knowledge available for our daily work of estimating the danger of individual cases. The mental habit, too prevalent in the profession, of regarding phthisis as a uniform, destructive, and irremediable disease, stands therefore in the way of obtaining the very kind of information likely to advance our knowledge of it, and of estimating the true duration of its several varieties. Difficulties Further difficulties will be found in the manner of obtaining du. taining information from the patients themselves, in the obscurity of the earliest symptoms of the disease, in the position of the different observers as regards locality, in the form of the affection commonly prevalent under their notice, as well as in the necessary limit to the experience of most medical men. in ascer ration of phthisis. The patient. 6 First, the answer of the patient to the question, 'How long ill?' will almost invariably be given, even by the most truthful, with reference to the existence of a group of symptoms which he fancies to be the most important. Thus, if cough have existed for six months with severity, or if the individual have been prevented from working for the same period by increasing weakness, the answer will be six months,' although a year or two previously he may have had hæmoptysis, attacks of sweating, or some grave alteration of health indicating the beginning of the tubercular affection. A A very careful cross-examination of the patient is absolutely necessary if the actual commencement of his disease is to be searched for. In hospital cases, especially if the first answer given be noted down, we are almost certain to record an error. Again, there are very few patients able to give in a single reply a correct description of |