=Points in the differential diagnosis between traumatic and other forms of coma.= The previous history of the case, the nature of the accident, and the lesions found may enable the surgeon to arrive at ready diagnosis. Often, however, it is impossible to exclude non-traumatic forms of coma without an exhaustive examination of the patient. In the process of examination, it is convenient to have in one’s mind a simple memoria-technica. Thus, A stands for Alcohol and Apoplexy. E „ „ Epilepsy (post-epileptic coma). I „ „ Injury. O „ „ Opium poisoning. U „ „ Uræmia. To this list must be added Diabetic Coma. Having these conditions in mind, the patient is examined from head to foot in the following manner:-- The _vault of the skull_ is first examined and all evidence obtained as to the presence and extent of external injury. The _ears and nose_ are investigated for escaping blood or cerebro-spinal fluid, important symptoms in the diagnosis of fracture of the base. The _eyes_ are next examined. Ocular palsies suggest injury or apoplexy; hæmorrhages--subconjunctival or palpebral--point to injury; whilst the condition of the pupils and disks may offer valuable information. Thus: In concussion, the pupils are equal, dilated, but responsive to light. In irritation, they are equal but contracted. In compression, they are either equal, dilated and fixed, or unequal. In alcohol, they are more or less normal, except in the deeper stages of intoxication, when they are dilated and irresponsive to light. In apoplexy, dilated and fixed, or unequal. Pin-point in pontine hæmorrhage. In epilepsy, usually equal and responsive. In opium, immovably and symmetrically contracted. In uræmia, dilated and sluggish. In diabetes, equal but dilated. React to light. In doubtful cases an examination of the disks may clear up the diagnosis. The presence of albuminuric retinitis, optic neuritis and atrophy (diabetes and uræmia), retinal hæmorrhages (injury), offer material diagnostic aid. The _tongue_ should be examined for such biting as is observed in epilepsy. The odour of the _breath_ is investigated--the sickly smell of alcohol, the sweetish odour of uræmia, the peculiar smell of opium, the chloroform-like smell of diabetes. The appearance of the _face_ may be suggestive. The unilateral facial palsy of trauma and apoplexy; the stertorous respiration, puffing out of the cheeks, and general turgidity of compression, uræmia, apoplexy and deep alcoholism; the quiet breathing and pale face of concussion, opium poisoning, and of post-epileptic and diabetic coma. The _urine_ should be examined for albumen and sugar, and the body and lower extremities for œdema.