_Shock._--Emotion; blows on the head or epigastrium; sudden evacuation of fluids from the body, as in emptying an over-distended bladder, tapping a hydrocele, ascites, or a pleural effusion. Extensive injuries to the body (railway and machinery accidents). Drinking large quantities of cold water when heated. _Exhaustive diseases_, chronic or infective. Symptoms.--Pallor of the face and mucous membranes, dimness of vision, cold perspirations, sense of impending death, restlessness, air hunger and gasping for breath, nausea, and, maybe, vomiting, noises in the ears, passing delirium, quick, feeble, and fluttering pulse, or the latter may be imperceptible at the wrist, insensibility, convulsions. In ordinary fainting attacks many of the above symptoms are absent; such as are present are temporary. In collapse, consciousness is retained. Post-mortem Signs.--The cavities of the heart contain a normal quantity of blood in death by asthenia, but may be almost empty when death is due to anæmia. The blood in asthenic death is simply arrested in its course; blood is, therefore, found in the large veins and in the arteries. The brain and the lungs are not engorged with blood. =Asphyxia.=--From ἀ priv. et δφνξιϛ, pulse. Apnœa is the better term--ἀ priv. et πνεω, I _respire_; but this word is now used by physiologists to denote a cessation of the respiratory movements due to artificially oxygenated blood. Blood in this condition fails to excite the respiratory centre in the medulla, and respiration ceases. To avoid confusion the term asphyxia had better be retained, especially as it is most commonly used and generally understood. Asphyxia, or death from defect in the quality of the blood, is brought about when any impediment is placed on the healthy action of the lungs. Experiment has shown that for a short time after respiration has ceased, the heart still continues to act, and that if the impediment to the proper aeration of the air by the lungs be removed, life may be prolonged. Taking therefore the primary meaning of the terms asphyxia and apnœa into consideration, it may be remarked that the latter precedes the former in point of time--asphyxia marking the period at which the action of the heart ceases, apnœa the cessation of the respiratory functions. _Causes of Asphyxia._--1. Mechanical obstruction to the air passages: foreign bodies, exudations, tumours, suffocation, strangulation, drowning, hanging, spasm of glottis from mechanical irritation, or irritant gases. 2. Interference with the action of the respiratory muscles: exhaustion of the muscles from cold; paralysis of muscles from injury to or disease of respiratory centre; poisons acting on the centre; continued pressure on walls of the chest; fixation of muscles from tetanus or strychnine poisoning. 3. Diseases of and injuries to the lungs: pleurisy with effusion, acute pneumonia, empyema, pneumothorax, pyopneumothorax, pulmonary apoplexy, embolism of pulmonary artery.