4. _Stage of paralysis._ Irregular cardiac and respiratory efforts, pulse grows rapid, coma deepening, muscular relaxation, pupils widely dilated, and permanent fall in blood-pressure. Respiratory paralysis. Treatment. (_a_) _Of concussion._ In considering the treatment of concussion, it has to be remembered that we are treating a condition dependent on vaso-motor depression, and that we are ignorant--at any rate for the time being--as to the nature and extent of a possible cerebral lesion. It is obvious, therefore, that although we are clear as to the general lines on which treatment is to be carried out, yet that our earlier methods must be expectant and our subsequent methods symptomatic. In other words, we must be prepared, at any moment, to change the method of treatment according as symptoms demand. The more general treatment--applicable to all cases, of whatever severity--consists in putting the patient to bed with the head low, in the application of warmth to the body and extremities, and in the administration of hypodermic injections of morphia, a drug of great value in the more severe cases of concussion. It must, however, be administered with caution, lest important symptoms be masked. Strychnine and brandy are practically useless. They merely whip the willing horse--the heart is doing full duty and cannot be further stimulated by such measures. In _mild and moderately severe cases_ this form of treatment will suffice to tide the patient over the collapse stage and induce the stage of reaction. So soon as this _commences_, the rising temperature and vomiting heralding the change, the head of the bed should be lowered, hot bottles and blankets removed--the patient being covered with a linen sheet only--and all forms of stimulant avoided. Calomel should be given by the mouth, 1 to 5 grains, according to the age of the patient. Headache may be relieved by applying ice-bags to the head, by tying round the forehead a handkerchief soaked in a weak solution of eau-de-Cologne, and by the administration of various drugs, more especially aspirin (10 grs.), antipyrin (10 grs.), and hyoscin (gr. ¹⁄₁₀₀). In _more severe cases_ more radical measures must be adopted to combat the severe vaso-motor depression, with its consequent splanchnic congestion and cerebral anæmia. No method is more desirable than infusion. This method, with its attendant advantages and disadvantages, has been detailed on p. 118. It is merely necessary to add that infusion must not be carried out in a haphazard manner. Its application is based on scientific principles, and its results must be noted with the greatest care. The surgeon must keep a watchful eye on the temperature and blood-pressure, and he must be prepared at any moment to change his plan of campaign.