COMPARATIVE MEDICINE

would be given to a patient weighing 150 pounds over the period of sevendays. Six cat units would supply the loss of digitalis in the six daysfollowing the day on which the drug was first given, and fifteen cat units would be required for the optimal amount to be anchored in the body. Many of Fahr's dispensarypatients are not seen until the lapseof a week. When the patient returnsand the pulse is over 70 while he is at rest and not excited, Fahr prescribestwo cat units daily until the rate declines to between60 and 70. When this rate is attained he gives one eat unit daily. In dispensary practice Fahr often administers the calculated optimal amount within a shorter period when the patient is badly decompensated. In his hospital practicehe generallyendeavoursto obtain the optimal effeet more quickly. As a rule he gives 1;; eat units to the 150-pound patient within the first thirty-two hours. One-third of the calculated quantity is given at once and one-sixthevery eight hours for four doses. An attemptis madeto maintain the ventricular rate at the optimal point by the exhibition of one cat unit daily when the optimal rate has been reachedat the end of from forty to forty-eight hours. When this rate has not been attained Fahr gives two cat units daily until the rate is between60 and 70. Thereafterone pat unit daily will generally hold the rate at this point. Fahr admits that there are some exceptions to his rules for the administration of digitalis. He observesthat occasionally digitalis seems to have no effect on conduction of the impulse from the auricles to the ventricles, and accordingly does not slow the ventricular rate. A small proportion of patientsexhibit toxic manifestationsbefore the optimal results in reducing ventricular rate can be attained. Somepatientsrequire more than one cat unit to ten poundsof body weight anchoredin the body in order to produce optimal slowing of the pulse rate. A very few patients require less than the calculatedoptimal dose. This is usually found in coronary diseaseor in other conditions that in themselvesreduceconductivity through the bundle of His. In hyperthyreoidism,as is well known, digitalis usually fails to lower the ventricular rate, and Fahr correctly remarks that its value is questionable. He very pertinently states that in toxic conditionsassociatedwith fever digitalis dosage should be smaller. It is unwise in such conditions to go beyond one-half of the usual dose. Fahr in his communication likewise deals exhaustively with the administrationof quinidine and its dangers,and also with paroxysmal tachycardia and heart block. His dissertation is particularly valuable.