_Treatment._--Diphtheria antitoxin is the specific treatment of this malady, and should be given early in the disease. The chances of recovery decrease in proportion to the length of time existing between the onset of the affection and the time of administration of the drug. Antitoxin may be repeated in six hours after the initial injection if improvement is not noticed, but ordinarily twenty-four hours should elapse between doses. It is well to remember that it is safer to give too much antitoxin than too little. The initial curative dose varies from 2,000 to 5,000 units, according to the age of the patient and the severity of the disease. When a case is seen late it is often advisable to begin with a large dose,--it being good practice under such circumstances to use at once as much as 10,000 units or even more. The average case requires from the beginning to the end of the treatment a total of from 10,000 to 20,000 units, but occasionally 50,000 or even 100,000 units may be necessary. There are very few risks in giving antitoxin. In a series of 50,000 cases treated with it only two deaths occurred sufficiently early after the injections to warrant the belief that this unhappy result was produced by the drug. It is worth remembering that asthmatic cases bear the administration of antitoxin very poorly; a marked and sometimes serious embarrassment of respiration, with cyanosis, unconsciousness, and general collapse may follow its use, but recovery is usual in such cases. A condition known as anaphylaxis or hypersensitiveness, which at present is being much studied, may sometimes occur in the human being. This hypersensitiveness is manifested by the extraordinary peculiarity that any number of doses of antitoxin may be given provided they are administered within a period of less than ten or twelve days. On the other hand a single minute dose may induce this state after the period named, and, as we never know whether a patient is going to develop it or not, it becomes a question as to the safety of giving a second injection after ten or twelve days have elapsed following the administration of the initial treatment. As it is true that this hypersensitiveness once established in animals may continue throughout life, it becomes a question as to whether or not it is quite safe to administer antitoxin to an individual who has had the drug given him at some prior time, and we are not as yet in a position to definitely determine the risks that are involved in such a procedure. There is no reason to doubt that this hypersensitiveness is much less marked in man than in the lower animals, and there can be no question that it much less commonly develops, but notwithstanding this it would be the part of prudence to avoid a second administration of the drug after the interval referred to in all instances where this seems possible.