present in the morning and disappear in the afternoon, only to recur upon the following day. Indistinct and indefinite râles may assume greater prominence following the temporary administration of potassium iodid.

Through the detailed application of the principles of palpation, auscultation, and percussion, irrespective of the newer and special aids to diagnosis, the nature of the tuberculous process may be recognized in many instances prior to positive bacteriologic evidences.

SPUTUM EXAMINATIONS

The discovery of tubercle bacilli in the sputum furnishes the most convincing proof as to the true nature of the pulmonary affection. While their presence may be regarded as conclusive evidence, their nonrecognition, save by an expert after repeated examinations, does not preclude their existence in the sputum. Their demonstrable absence from a single specimen, even following an exhaustive search in accordance with a careful technic, affords no absolute information as to the non-tuberculous character of the affection. The all too prevalent habit of delaying the diagnosis of consumption until the appearance of the bacillus is a practice calculated to relieve the physician of a portion of his ostensible responsibility, but in reality this constitutes a technical evasion of his moral obligation to the patient. The most pernicious feature of a diagnosis, founded exclusively upon the discovery of bacilli, relates to the unnecessary delay before remedial measures are adopted. This laxity is fraught with very considerable danger to the invalid, who, resting in a position of false security, loses not only valuable time, but a measure of opportunity as well, in the struggle to secure arrest after the so-called open stage of tuberculosis has developed. It is true that there is a certain burden of responsibility imposed upon the physician, who assumes to diagnose pulmonary tuberculosis without incontrovertible bacillary evidence of its existence. This obtains particularly on account of the radical advice necessarily given with reference to methods of living, suspension of work, change of occupation, severance from family, and recourse to favorable climates. On account of the involved responsibility and through motives of personal interest in the invalid and family, the clinician may often hesitate to pronounce sentence without the corroborative evidence furnished by bacilli. In cases in which the combined subjective symptoms and signs are strongly suggestive of a tuberculous process, there can be no greater dereliction of duty on the part of the physician, than to withhold the diagnosis until the appearance of bacilli. On the other hand, in the absence of clearly defined indications of tuberculous infection, an unqualified positive decision should not be reached through the uncertain interpretation of a single factor, even though possessed of considerable clinical interest. Among those who are apt to pride themselves upon a refinement of diagnosis, there seems to be a growing tendency to advocate unreservedly the rendering of an affirmative. opinion entirely independent of the bacilli. In the interests of the profession and of humanity it is time a note of warning was sounded, for fear lest, in the midst of ultrascientific enthusiasm and through commendable pride in detailed clinical study, the swing of the pendulum may eventuate in ill-sustained notions, causing unnecessary suffering and

embarrassment to the supposed pulmonary invalid. It is well to maintain, as far as possible, a rational and moderate attitude with reference to the discovery of bacilli before making an unqualified diagnosis of consumption. Results which ultimately are to be satisfactory to the patient, relatives, and to the physician himself will be attained only through a careful weighing of all the evidences presented and a judicial determination of their combined import. A practical objection to withholding invariably the diagnosis until the recognition of bacilli arises from the fact that there are a considerable number of physicians who, through insufficient training and inadequate technic, are unable to detect bacilli until they are present in large numbers and the disease has correspondingly advanced. Another though less frequent source of error relates to the detection of supposed tubercle bacilli by superficial observers. It thus appears that the practical value of the sputum examination, no less than of the physical exploration, depends upon the ability and training of the examiner. The selection of barren particles of sputum, the making of a thick and uneven smear, carelessness in staining, insufficient decolorizing, and haste in the microscopic search, are among the more common causes of mistaken conclusions regarding the presence of bacilli. The manner of examination previously described may be modified by combining the decolorization and the counterstaining according to the method of Gabbet. After the initial stain is washed with water, this consists of drying the cover-glass for a few seconds in a solution composed of 25 c.c. sulphuric acid, 100 c.c. water, and 2 milligrams methylene-blue, following which the glass is again washed and examined after drying. The only advantage gained, which is very slight, relates to the shortening of the process, but the results are not quite so satisfactory as with the method described in an earlier chapter. If the bacilli are found to be absent after several examinations, more conclusive results may be obtained by treating the sputum with a solution of soda or potash and centrifuging.

CHAPTER XL

SPECIAL AIDS TO DIAGNOSIS

FOR general purposes the diagnosis can be made with sufficient accuracy and celerity without recourse to the newer methods or special aids. Delay has been occasioned, in the vast majority of cases, not through inability to utilize these methods, but on account of failure to recognize the ample subjective and objective clinical data already available. There are many difficulties in the way of establishing an exact and early diagnosis through the agency of special methods, the necessary restrictions upon their employment placing them beyond the immediate reach of the general practitioner. They may be regarded, however, as of value in very exceptional and obscure cases. The newer methods of diagnosis of special importance relate to the use of the tuberculin tests, animal experimentation, and the Röntgen-rays.

THE TUBERCULIN TEST

Save under very puzzling conditions, recourse to the old tuberculin of Koch by subcutaneous injection is quite unnecessary and unwarranted. When the diagnosis is sufficiently clear by other means, the tuberculin test presents no additional feature of value, while its employment, unless in the hands of a careful and experienced physician, is vested with certain possibilities of danger. Shortly after its introduction by Koch it was proclaimed by several students, as a result of considerable research and clinical observation, that the tuberculin served to renew the activity of previously latent foci, and to disseminate a general tuberculous infection. Radically differing views were entertained by pathologists as to its possible influence, at a time when it was used in larger doses than in recent years. It may be assumed at present that the tuberculin in carefully graduated doses in the hands of a skilled clinician is entirely harmless, the only danger resulting from its indiscriminate and careless administration. In like manner the possibility of correct conclusions following its use depends entirely upon a rigid adherence to certain precautionary measures, the reaction, if present, being of much or slight significance according to the conformity of its employment to certain well-recognized principles. The production of a general reaction, marked by temperature elevation and more or less constitutional disturbance, together with occasional local manifestations, constitutes the basis of the test. Some opposition to its use arises from the exhibition of a positive reaction in cases apparently not tuberculous, the variable degree of the reaction, and sometimes, though rarely, its entire absence in infected individuals. It is important to note, however, that when the reaction has occurred in the supposedly non-tuberculous, autopsy findings have often disclosed the presence of concealed foci of inactive infection. While this partly accounts for its exhibition among apparently healthy people, the very fact of latent tuberculosis among a large portion of the race detracts to some extent from the significance of the reaction among individuals suspected of early pulmonary lesions.

The occasional absence of reaction among the tuberculous is explained largely by failure of less practised observers to conform to a strict technic in the manner of its employment. The reaction has been found to be more pronounced in recent cases, and comparatively slight among the far advanced, the increased tolerance among the latter suggesting an effort of nature toward the establishment of partial immunity. It is possessed of but little diagnostic significance if administered in the presence of even slight elevations of temperature, a fever of over 99° F. being sufficient in many cases to preclude accurate diagnostic interpretations. Inasmuch as the reaction may be attended by fever ranging from one to three or four degrees above normal, it is readily apparent that a detailed record of the temperature, for several days preceding its administration, is essential. Before employing the test the temperature should be taken at not less than two-hour intervals during a period of two or three days, preferably a week, in order to avoid any confusion arising from ordinary fluctuations.

The reaction usually occurs in the neighborhood of the tenth hour, but may be delayed until the second day. It is sometimes accompanied by symptoms of more or less profound constitutional disturbance of one

ance.

or two days' duration, consisting of chill, headache, pain in back, limbs, and joints, nausea and vomiting, malaise, and general restlessness. These symptoms usually subside after a few hours. A local reaction, which is capable of recognition, is of more significance than the general disturbWhile the local manifestations are often of pronounced character in tuberculous involvement of the bones, joints, glands, and testicle, the detection of definite change in the areas of pulmonary infection is not always possible. My experience with the old tuberculin for diagnostic purposes has been very limited, having used the test as a last resort in but a very few doubtful cases. Ample opportunity has been afforded, however, to witness marked local reaction following the administration of the bacilli emulsion for therapeutic purposes. During the past year this agent has been given extended employment in selected cases. Thus means have been acquired for a study of the local reaction in a few conspicuous instances. In connection with the not uncommon aggravation of cough and the added amount of expectoration there has been found in some instances upon auscultation a temporary increase of moisture in infected areas. With the bacilli emulsion I have not been able to detect an appreciable modification of the former respiratory sounds, but this is reported to have been recognized at times after injection of the old tuberculin.

In making use of the diagnostic test the beginning dose should not exceed of a milligram, although some clinicians are accustomed to employ initial doses of two or three milligrams. There is nothing particularly to be gained by adopting the larger dose in the beginning, which in many cases results in extreme discomfort to the patient and presents certain elements of danger. If there is no reaction following its initial administration, a second dose may be given after the lapse of several days, during which time the temperature should be recorded with care in the same manner as prior to the first injection. In case of failure to react after smaller doses they may be gradually increased up to six or seven milligrams. It is not advisable to exceed this dose in any event, and very rarely justifiable to resort to over two or three milligrams. The only objection to the use of the smaller doses is the possible establishment of a gradual tolerance on the part of the system and the consequent failure to secure reaction. An intelligent use of the tuberculin demands the exercise of the utmost care in adjusting the size of the dose. This arises partly from the necessity of diluting the crude product. It is well to make the dilution at the time of its administration, as the product becomes inert after remaining diluted for more than forty-eight hours, although some continue its use for two weeks after it has been prepared. The best method of dilution is the use of 0.5 per cent. of phenol in distilled water. All the appliances employed in its administration, which include the syringe, tubes, pipets, etc., should be made absolutely sterile by boiling, preceding each injection. The most rigid aseptic precautions are necessary to avoid the unpleasant consequences of infection. Those who make frequent use of the tuberculin for diagnostic and therapeutic purposes are found to favor various sites for the point of injection, but it is extremely doubtful if this is of special moment. It is usually better to make the injection deeply into the muscle of the back rather than subcutaneously. The skin should be thoroughly cleansed and rendered aseptic with alcohol or ether.

A sterile pad should cover the point of injection for at least

twenty-four hours. Inhalations of tuberculin for diagnostic purposes by means of a specially devised vaporizer have recently been employed, but the results thus far are insufficient to justify conclusions other than as to the convenience of the method.

While the legitimate scope of the tuberculin test, when employed subcutaneously for diagnostic purposes, is extremely small, and its field of usefulness confined exclusively to a few doubtful cases otherwise incapable of precise determination, it, nevertheless, is safe to conclude that its intelligent employment in this manner is not only harmless, but possessed of a high degree of diagnostic value.

A recent important modification of the tuberculin test has been introduced by Calmette and Wolff-Eisner, known as the ophthalmotuberculin reaction. By means of this method the tuberculin test represents a most valuable aid to diagnosis, and its careful employment seems to be divested of all disagreeable or dangerous features. The principle upon which is based the topical application of tuberculin for diagnostic purposes is found in the local reaction exhibited by infected individuals following the administration of the toxins of the tubercle bacillus. This sensitiveness of the tissues was noted long ago following the use of Koch's old tuberculin. While local lesions were by no means uniform, the frequency of hyperemia and swelling at the site of injection was often the subject of comment. Also in animal experimentation it was noted, as stated in other chapters, that in many instances an acquired partial immunity after primary inoculations was suggested by the more intense local reaction attending the second injections. Reference is made in the chapter upon Immunity to the action of the toxic substances in the presence of the tuberculous foci of infected individuals. The development of local lesions following the subcutaneous employment of tuberculin suggested a response of the tissue-cells as a result of the absorptive products from the foci of infection.

The first practical application of these principles of local reaction in tuberculosis was made by von Pirquet, who, after scarification, made topical application of tuberculin and noted localized swelling and congestion in tuberculous children. Calmette subsequently utilized the same principles by applying tuberculin to the conjunctiva. By the use of 95 per cent. alcohol he precipitated the tuberculous toxins from Koch's old tuberculin. After drying and dilution with 1 per cent. sterile water or normal salt solution, one drop was instilled into the eye. In from three to eight hours this was followed in tuberculous individuals by a local reaction, varying from a slight redness of the caruncle to an intense hyperemia of the conjunctiva, with considerable secretion and at times. edema of the lids. The reaction remained well defined for three or four days, but rarely persisting for longer than a week. Among nontuberculous individuals either a negative result was noted or else the reaction was mild and of short duration. The test has been applied by a considerable number of observers, who have reported in the main fairly uniform results corroborative of the conclusions of Calmette. Baldwin has recently reported his observations concerning the efficacy of this test, as made upon 137 cases, including 62 observed by Drs. Trembley, Allen, Twitchell, Brown, and Rathbun. Nearly all the individuals known to be definitely tuberculous displayed a positive reaction, the only exceptions being a case of miliary tuberculosis, a patient being treated with tuberculin, and a doubtful case with healed