Till, therefore, more evidence comes to hand with respect to heat-regulation in general, one cannot go beyond the broad statement that, in severe head-injuries, definite temperature changes occur, that the changes are independent of any special lesion of bone or brain, that they are generally associated with some brain-injury, and that they are probably due to the influence exerted by the lesion on the heat-regulating centres in the region of the pons and bulb. With regard to the value of the temperature, both with respect to prognosis and treatment, a very much more definite statement can be made. First with respect to the =prognosis=. All cases of head-injury may be grouped into four classes, according to the changes of temperature present. _Group 1._ The temperature, at first subnormal, undergoes a rapid and progressive rise. Prognosis most unfavourable. _Group 2._ The temperature, at first subnormal, rises gradually to 101° or 102° and there ‘marks time’. This hesitancy marks the crisis of the case, further elevation indicating a fatal result, whilst a fall offers every hope of recovery. _Group 3._ The temperature, at first subnormal, rises to normal and remains at that level. Prognosis very favourable. _Group 4._ The temperature, at first subnormal, remains subnormal. The condition of shock persists, and the prognosis is most unfavourable. Practically all cases of head-injury fall readily into one or other of these four groups, and the temperature chart presents so clear a picture that it must be regarded as of the greatest possible value in estimating the prognosis in any given case. In other words, the temperature chart affords an almost infallible guide both to prognosis and treatment. With respect to alteration in temperature on the two sides of the body, the clinical value of such changes must, from my own observations, be regarded as of a very indefinite nature. It now remains to discuss the value of temperature changes with respect to treatment. =Treatment of Fracture of the Base of the Skull.= In the earlier paragraphs of this chapter the special treatment of aural and nasal hæmorrhages and cerebro-spinal discharge was discussed, and some allusion was made to the necessity of exploring the middle fossa in cases of profuse arterial or venous aural bleeding. The general treatment of basic fractures now requires description, previous to which, however, space must be made for a short account of the routine treatment by Urotropin--as advised by Crowe and Cushing--as a prophylactic against the development of meningeal infection. The following is a summary of Crowe’s paper[25] on the ‘excretion of Urotropin in the cerebro-spinal fluid and its therapeutic value in meningitis’. 1. Urotropin, when given by the mouth, invariably appears in the cerebro-spinal fluid. 2. The largest amount of Urotropin is present in the cerebro-spinal fluid from thirty minutes to an hour after the ingestion of the drug.