=Jaundice.=--It is well known how exceedingly dangerous an operation upon a jaundiced patient may be owing to the difficulty of obtaining hæmostasis. The coagulation time of the patient’s blood is not affected in a transient catarrhal jaundice, but in the chronic condition it has been shown to be three or four times the normal (223). In these circumstances it is found that a transfusion is of some use in shortening the coagulation time of the patient’s blood so that bleeding ceases, although sometimes, especially in cases of jaundice due to malignant disease in which the biliary obstruction has not been relieved by the operation, the effect is very transitory, and after two or three days the patient may again begin to bleed (215). No other method of overcoming this has yet been found to be more effective than transfusion, though the intravenous administration of calcium compounds is sometimes of value. =Hæmophilia.=--Blood transfusion is of still greater value when the coagulation time of the blood is prolonged owing to a congenital deficiency, as in hæmophilia. It is unnecessary to discuss here in detail the precise nature of the deficiency. No definite conclusion has yet been reached, though it seems to be clear that the abnormality resides in the organic clotting complex, and not in the calcium content of the blood. Treatment, therefore, will aim at supplying the deficient substance, so that the coagulation time may be reduced to normal, whereupon the bleeding will cease. Various methods of bringing this about have been used. Horse serum or whole blood injected subcutaneously has often been found effective and sometimes even when used merely as a local application. Not infrequently, however, horse serum fails of its effect, so that no reliance can be placed upon it. Even when effective, the alteration in coagulation time is transitory, a fact which introduces an obvious objection to its use, for if the occasion should arise, as it easily may, for a repetition of the treatment, the patient may be exposed to the risk of severe anaphylactic shock. Another form of treatment has been introduced by H. W. C. Vines, in which a slight anaphylactic shock is deliberately induced, the result of this being a fall in the coagulation time of the blood to normal. The mechanism of this change is at present unexplained. Again, the effect is transitory, but for a certain period afterwards a surgical operation may be safely performed upon a hæmophilic patient treated in this way. This method has not yet been extensively tested, and in any case it cannot be used in an emergency, for the patient must be sensitized by a preliminary injection and an interval of several days allowed to elapse before the anaphylaxis can be produced.