The subject of Sercus Meningitis as a distinct and separate disease is even to -day not quite clearly defined and the principal reason for this is that, owing to the relative scarcity of cases, the clinical picture of the disease has not been worked out by the Authorities to the same extent as other forms of Meningitis.Serous Meningitis is a disease which may occur spontaneously or in connection with some infective disease in the system. It is due to some irritation whether by Toxiues or other cause. It is characterised by the effusion into the ventricles of a large quantity of clear sterile fluid, which may come on suddenly or more slowly, so that we recognise an acute and a chronic form.It must also be noticed that at first we may have effusion into the eubarachnoid space, which is gradually forced out by the expansion of the brain substance so that an external and an internal variety has been described. The symptoms are mainly those due to an increase in the intra cranial pressure and are rather those of compression than of irritation, with paralysis usually spastic, without fever, and without as a rule, any localising symptoms; unless relieved the -condition: passes into coma and death.The diagnosis can only be definisa.xtely made by the withdrawal by means of the needle of a large quantity of clear sterile cerebro spinal fluid at high pressure.The treatment consists in removing the excess of the fluid by lumbar puncture to be repeated, if necessary, whenever there are signs of an increase in the intracranial pressure. But that under this treatment the prospect of recovery is good.Finally, in one particular, my case is deficient, and that is in the pathalogical report: nor do I regret it.By Quinche's great discovery this boy, after being for months unable to move a hand or foot, after enduring the most intense agony, after being prepared and indeed anxious to die in order to be relieved of the pain, has been restored to perfect health ( save for his sight) and is now leading a useful and contented life.