_Opisthotonos_, from the involvement of the posterior divisions of the upper cervical nerves, sometimes of so excessive a nature that the body is bent backwards to such a degree that the head and heels are almost brought into contact. More rarely, pleurosthotonos or lateral flexion is observed. =Sensory and other phenomena.= Amongst such symptoms may be mentioned cutaneous hyperæsthesis, photophobia, and vaso-motor changes--the last-named evidenced by flushings, sweats, and _tâche cérébrale_. Rapid emaciation, anorexia, and distaste for all nourishment are the rule, whilst retention of urine, albuminuria, and glycosuria have been observed. The reflexes, both deep and superficial, are often increased. Kernig’s sign is generally present. =The period of depression.= The acute stage seldom persists more than two or three days, the period of excitation giving place to that of depression. The transition is usually of a rapid nature. The depression stage is dependent on exhaustion of the cortical and basal centres. The temperature remains high, rising towards the evening and falling a degree or more in the early hours of the morn. Death usually takes place when the temperature is at its highest. The pulse may become slower as the intracranial pressure increases, but, more commonly, as the result of toxic poisoning, the rate increases whilst the rhythm becomes irregular and the tension lowered. Respiration may partake of the Cheyne-Stokes type, whilst the impaired æration of the blood and the weak action of the heart are evidenced by cyanosis of the face, œdema of the lower extremities, &c. Death, primarily due to respiratory failure, is often preceded by general twitchings or convulsions. The whole course of the illness seldom lasts more than a week, the more acute cases terminating within two or three days. =Treatment.= Whether threatening, developing, or obviously present, the patient should be treated with urotropin (see p. 116). In its early stages of development immediate operation affords some hope of cure, such treatment having as its basis the supply of adequate drainage. The source of the infection must be removed--so far as circumstances permit--the dura mater freely incised, and the pia-arachnoid region so opened up as to allow of the escape of some of the purulent or semi-purulent fluid. The wound is largely allowed to remain open, packed with gauze. The predominant organism may be isolated and, if time allows, suitable vaccine treatment instituted. In the meantime, 20 to 40 cc. of pyogenes serum should be administered. From the point of view of diagnosis, _lumbar puncture_ should never be omitted. The fluid escapes at high tension, is turbid and contains many polymorphonuclear leucocytes and organisms, the latter verified with the greatest advantage after centrifugalization. Repeated lumbar punctures are also said to be of some benefit with respect to _treatment_. SINUS THROMBOSIS