are caused by the character of the epidemy, but, perhaps, more frequently by the weak and sickly constitution of the patient and the external circumstances affecting it. Thus, persons of scrofulous habit, being naturally of a low organization, without much power of resistance, are much more liable to experience the destructive effects of scarlatina than those whose organism possesses sufficient energy to resist the action of the morbid poison, and to expel it before it can do any serious harm inside the body. 17. SUDDEN INVASION OF THE NERVOUS CENTRES. Of the different forms of scarlatina maligna the most dangerous is the sudden invasion of the nervous system, particularly the _brain_, the _cerebellum_ and the _spine_, by which the patient's life is sometimes extinguished in a few hours. In other cases the symptoms deepen more gradually, and death ensues on the third, fifth or seventh day. 18. AFFECTION OF THE BRAIN. When the _brain_ is affected, the patient suddenly complains of violent headache, vomits repeatedly, loses his eye-sight, has furious delirium, or coma (a state of sleep from which it is difficult to rouse the patient); his pupils dilate; the pulse becomes small, intermits; sometimes the skin becomes cold; there is dyspnoea (difficulty of breathing), fainting, paralysis, convulsions, and finally death; or, sometimes, the paroxysm passes suddenly by with bleeding from the nose or with a profuse perspiration. 19. AFFECTION OF THE CEREBELLUM AND SPINE. In affections of the _cerebellum_ and _spinal marrow_, the patient complains of violent pain in the back of the head and neck, in the spine, and frequently in the whole body. These also frequently terminate with the destruction of life. 20. During all these invasions of the nervous centres there is little or no rash, and what appears is of a pale, livid hue. 21. PUTRID SYMPTOMS. Next to those most dangerous forms--most dangerous, because the organic power (the _vis medicatrix naturae_), from which the restoration of health must be expected, and without which no physician can remove the slightest symptom of disease, becomes partly paralyzed from the beginning--_putrid symptoms_ present a good deal of danger, although they give the organism and the physician more time to act. 22. CONDITION OF THE THROAT, AND OTHER INTERNAL ORGANS.