ment, may mask the symptoms of disease, or give rise to additional phenomena that, unless caution be exercised, may lead to error in diagnosis.

The data for diagnosis are obtained by observation and inquiry. Inquiry may often have to be made of those about the patient, the latter being unable or incompetent to answer; and not rarely the same questions will have to be repeated in various ways and be controlled by questions requiring opposite answers, in order that the clinician be not deceived, intentionally or otherwise.

Observation can be made while the questioning is proceeding; sometimes the manner, method and form of a patient's answers to questions are in themselves part of the data acquired by observation. For example, in cases of aphasia, the patient is unable to find words in which to express himself, though he may understand the questions put and may even believe that in his monotonous repetition of certain words and phrases he has given an intelligent answer.

Observation includes (1) a more or less rapid survey of the general condition of the patient, and (2) a careful examination into the condition of special structures, the performance of special functions and the constitution, chemic and microscopic, of the blood, the secretions and the excretions, both as to normal and abnormal constituents.

The whereabouts of the patient may afford information as to the acuteness or severity of the attack. He may be attending to his work as usual, or he may be confined to his house, his room, his bed.

Position and movement are next noted. Thus, if the patient paces restlessly about, a condition of excitement, of physical or mental causation, is indicated. If, whether seated or recumbent, his position is easy and unconstrained, it indicates that, whatever the disease may be, the attack is, for the time being, mild and that there is no serious respiratory or circulatory trouble, or inflammation of an important part. If the patient lie passively upon his back, or huddled up in a heap, a prostrating sickness, usually an acute infectious disease, is indicated. If he lie persistently on one side, affection of the lung or pleura of that

side is likely to exist; because this position restrains the movement of that side of the thorax, lessens the pain of acute inflammation and, in addition, permits the healthy lung to better perform its work. Sometimes, however, patients with pneumonia lie on the sound side, having less pain in that posture.

If, whether the patient be in an easy-chair, or in bed, the thorax is propped into an upright or semi-upright posture, there is great difficulty in respiration (orthopnea), which may be be due to cardiac or pulmonary disease, to obstruction in the upper air-passages, or to abdominal or general effusions. If the patient lie upon his back with the legs drawn up, there is likely to be peritonitis, and if on the right side with the right leg drawn up, appendicitis should be suspected.

If the head is retracted, or fixed in opisthotonos, disease of the cerebrum or of the meninges is to be suspected. So, too, deviation of the head to one or the other side, picking at the bedclothes, helplessness of one or more extremities, general restlessness, jactitation, local spasms or general convulsions, incoördination, tremor, temporary or persistent, sometimes throw considerable light on the condition of the nervous system. The expression of the countenance should be observed. It may be indicative of comparative comfort or of intense suffering; it may be dull and apathetic, as in typhus fever; sunken and anxious, as in cholera; eager and brilliant, as in some cases of pulmonary tuberculosis; indeed, a careful study of the physiognomy of patients may often directly reveal much, or indirectly serve to lead the attention of the examiner to matters that might otherwise be overlooked. Thus, there is in many cases of chronic nephritis a peculiar pallor that can hardly be mistaken by the experienced observer. Connected with the expression of the face are the general nutrition, the condition of the skin, and the condition of the mind, all of which must be included in the general examination.

Concerning the mental condition, without special effort it can be learned whether the patient is interested in his surroundings or is oblivious to them, whether he is conscious or unconscious, whether he is delirious or is aware of his sayings and doings, whether he is able to fix his attention or is continually wander

ing. To the facts developed on special inquiry no attention is now being paid.

The skin may be of normal hue, pallid from impoverishment of blood, flushed with fever, discolored by inflammations, bruises, extravasations, eruptions, jaundice, the various cachexias. It may be swollen, or give evidence of swelling or effusion beneath. It may be abnormally smooth or rough, dry or moist, hot or cold.

The state of the nutrition is usually evident in the preservation of the full, rounded outlines, or in the sharpness and hollows of emaciation. For accuracy and completeness of knowledge the weight should be determined by the scales.

Abnormal prominences of various kinds and situation may indicate the existence of tumors, effusions, articular, osseous, glandular and visceral enlargements of inflammatory or other origin, to be determined by further examination.

Pulsations may be visible that, by their abnormal situation or abnormal character, are indicative of abnormal circulatory conditions, or of tumors or collections of fluid external to the heart or vessels. The tortuosity of visible arteries, or the localized or general turgescence of superficial veins, may indicate disease or obstruction in or affecting the circulatory apparatus.

The manner in which breathing is performed, the character of the voice, the nature of a cough, afford information as to the condition of the respiratory apparatus.

Examination of the pulse, the tongue, and the temperature, while affording general indications, yet mark the transition from general to special examinations.

Except in a few instances, the plan of this book does not contemplate descriptions of methods of special examination, or enumeration of the conditions indicated by special symptoms and signs (semeiology, inductive diagnosis), but rather an account of the observed clinical groupings of signs and symptoms in the recognized and named affections of nosology (historical diagnosis, pathological association diagnosis), and an elucidation of the points of contrast between diseases most likely to be confounded (differential diagnosis).

What is fever?

FEVER.

Fever is a complex morbid process, of which the most striking feature is elevation of temperature. Sometimes the term fever is restricted to the abnormal heat, but this is more correctly termed pyrexia. In addition to pyrexia, fever is attended with acceleration of the pulse and of the respiration, with thirst and with disturbance of digestion. There are likewise increased and perverted tissue-changes, as manifested by alterations of secretions and excretions, which may be completely arrested or diminished in quantity and changed in quality. As a result of the deprivation of the normal products of metabolism and of the retention in the blood of abnormal products of metabolism, as well as of the waste-products of normal metabolism, other symptoms are often caused, such as malaise, depression, headache, insomnia, delirium, etc. When fever is long-continued, wasting takes place; partly as a result of the abnormal heat, both directly and indirectly; partly from other causes. Many febrile processes are at some period in their course attended with subnormal temperature.

What is the average normal temperature of man?

The average normal temperature of the adult is 98.4° or 98.6° F. (37° C.); in health it may vary from this a little more than a degree; from 97.3° F. (36.25o C.) to 99.5° F. (37.5° C.). It is higher in children than in adults, and in the aged it is sometimes a few tenths higher or lower.

The temperature is increased after meals by the activity of digestion; it is increased by exertion, and in children and hysterical persons by emotion. Weather has but slight influence upon the temperature of the healthy; it often has a marked influence upon that of the sick. There are daily periodic variations. The daily minimum occurs in the early morning between two and five o'clock; the daily maximum is reached between five and eight o'clock in the evening. The average difference between maximum and minimum is about 1.5° F.; it may be much

more. In the tropics the average body-heat is said to be slightly higher, and the daily range greater than in temperate climates.

In sickness the diurnal variations (morning remission, evening exacerbation) become quite marked.

What is subfebrile temperature?

The term subfebrile temperature is not to be confounded with subnormal temperature. It is applied to a moderate morbid elevation of temperature not exceeding 100.4° F. (38° C.).

What is the ordinary range of febrile temperature?

A temperature of from 100.4° F. (38° C.) to 101.2° F. (38.4°C.) is considered an indication of slight fever.

A temperature of from 101.3° F. (38.5° C.) to 102.2° F. (39° C.) in the morning, and of 103° F. (39.5° C.) in the evening, is indicative of moderate fever.

Á temperature of from 103° F. (39.5° C.) to 104° F. (40° C.) in the morning, and of 105° F. (40.5° C.) in the evening, indicates high fever.

What is hyperpyrexia?

Febrile temperature exhibiting a tendency to remain above 1070 F. (41.7° C.) is called hyperpyrexia. This is ordinarily directly dangerous to life.

Very high temperatures have been observed in hysterical cases in which, apparently, deception has been guarded against; a case of injury to the spine, in which recovery took place, is reported to have exhibited on many occasions a temperature of 1220 F. (500 C.).

What is meant by inverse temperature?

Ordinarily the course pursued by morbid temperature is like that of normal temperature in having its maximum towards evening, and its minimum in the early morning. Sometimes, however, the maximum may be much earlier or much later than usual, even at noon or at midnight. Sometimes there are great fluctuations during day and night. When a complete reversal takes place, so that the morning temperature exhibits the maxi