FIG. PAGE 22. Micrococci of Croupous Pneumonia (Vierordt) 21. Pulse-tracing of Aortic Insufficiency (after Strümpell) 124 23. Tubercle-bacilli in Sputum (Ziegler) 29. The Relations of the Heart, Lungs, Liver, Stomach and Spleen, as seen from the front (Weil) 223 32. Uric Acid and Urates (Funke) 30. Showing the Relations of the Lungs, Liver, Spleen and Kidneys, as seen from behind (Weil-Luschka). 31. Relations of the Spleen (Weil) 33. Calcium Phosphate (Laache) 34. Triple Phosphates and Ammonium Urate (Laache) 37. Red Blood-corpuscles and a Blood-cast of a Uriniferous 251 251 38. Epithelial Cast of a Uriniferous Tubule (v. Jaksch) 39. Granular Casts of the Uriniferous Tubules (v. Jaksch) 40. Hyaline Casts of the Uriniferous Tubules (Vierordt). 41. Waxy Casts of the Uriniferous Tubules (v. Jaksch) 42. Filaria Sanguinis Hominis (v. Jaksch) 43. Multiple Neuritis-Wrist-drop and Foot-drop (Gowers) 277 44. Facial Paralysis (Gowers) . 252 253 224 240 244 245 246 247 280 45. Progressive Muscular Atrophy (Gowers) 294 46. Pseudo-hypertrophic Paralysis in two brothers (Gowers) 297 47. Pseudo-hypertrophic Paralysis. Mode of rising from the ground (Gowers) 298 48. Paralysis Agitans (after St. Leger) 307 49. Appearance of the Hand in Morvan's Disease (after 51. Wrist-drop from Lead-poisoning (Gowers). 337 FIG. 52. Mode of holding the pen favorable to the development Method of holding the pen when writing becomes dif- 53. Exophthalmic Goiter. Defective descent of the upper lids on looking down (after Wilks) 54. Akromegalia (after Marie) 55. Outline of the Face: 1, In Myxedema; 2, In Akromegalia; 3, In Osteitis Deformans (Marie) PAGE 340 340 352 356 357 ! ESSENTIALS OF DIAGNOSIS. INTRODUCTION. DIAGNOSIS, in medicine, is the art and science of observing and of discriminatingly interpreting the phenomena of disease. In its study, a knowledge of the phenomena of health is an essential prerequisite. Unless familiar with the sounds elicited upon percussion of the normal chest, one cannot decide whether or not the sound heard in a given case is indicative of abnormal conditions. Unless one knows the characteristics of normal urine, he cannot hope to gain from urinalysis a clue as to the nature of a case of disease. Unless one knows the appearance of a healthy brain, he cannot determine whether the brain seen at a necropsy is or is not the seat of morbid change. Unless one knows the function of a normal joint, he cannot affirm that a joint under investigation has had its function impaired. Having learned, by observations upon the healthy, to recognize when departures from health have taken place, one must further learn by observation of the sick to appreciate the significance of such departures. No opportunity should be lost to examine post mortem the organs and tissues that have been altered by disease. A knowledge of the effects of drugs upon healthy and unhealthy persons and organs may likewise render easy a diagnosis that might otherwise be difficult. The phenomena indicative of the existence of disease are in a general way termed symptoms. These may be either subjective— known only to the patient by his sensations; or they may be objective-capable of investigation by the senses of the observer, aided, it may be, by instruments of precision. Thus pain, vertigo, nausea, ringing in the ears, are subjective symptoms, while high temperature, vomiting, unsteadiness of motion, loss of voice, are objective symptoms. The objective manifestations of disease may be further divided into symptoms (in a restricted sense) and signs. While the two are not rigidly separable, symptoms may be defined as manifestations of disordered function, signs as manifestations of altered structure. Thus, cough is a symptom; the laryngeal congestion discovered by inspection with the mirror, the bronchial râles heard upon auscultation, are signs. Difficulty in deglutition is a symptom; a pulsating tumor in the chest, indicative of aneurism pressing upon the esophagus, is a sign. Dyspnea is a symptom; distension of the abdomen with gas (tympanites) or with fluid (ascites), causing pressure upon the diaphragm and restricting its movements, is a sign. Thus, signs are in many cases directly explanatory of symptoms, and their discovery is one step further in the diagnosis. It must not be forgotten, however, that signs are not always to be found; that, when found, a sign may not account in toto for the symptom with which it is associated; and that even when sufficient to explain the symptom, the sign itself remains to be explained before the diagnosis is complete. Like all other morbid phenomena, signs must, therefore, be considered in relation with all the evidence presented in a given case. Certain signs that are not at once manifest, but that require for their study special means of exploration, are termed physical signs. In its restricted sense, the term "physical signs" is applied to the phenomena elicited by special methods (inspection, mensuration, palpation, percussion, and auscultation), used chiefly in examination of the chest and abdomen, though often applied elsewhere; while the signs elicited by examination of the blood, the urine, the sputum, the feces, or by laryngoscopy, ophthalmoscopy, cystoscopy and the like, are not given other qualifying designation than the special names describing the respective processes. Phenomena corresponding with logical deductions as to the direct results of deranged function, including subjective and |