There was another difficulty, however, in the way of the adoption of antitoxin that had to be overcome, one that proved no little source of discouragement to many of those who were testing the remedy. The original diphtheria serum employed was not concentrated; so when a sufficient amount of antitoxic units to neutralize the toxins of the disease under treatment was employed, a large quantity of serum had to be injected. Experience shows that the injection of any foreign blood serum into an animal is followed by a certain amount of haemolysis, or blood destruction, and by {347} certain cutaneous manifestations, such as urticaria, erythemata, the familiar hives-like eruption and red itchy spots, which prove a great source of annoyance. In very susceptible cases the injection of even a small amount of foreign serum is followed by some fever, by restlessness, and red and swollen joints. In the early days of the employment of diphtheria antitoxin, all of these complications were noted in many cases. They were sufficient to make many who were interested in the demonstration of the value of antitoxin so disappointed and discouraged that they gave up the task. Not so, however, with O'Dwyer, who continued its use, and encouraged others by his example so that in spite of these objections antitoxin obtained a firm foothold. Dr. O'Dwyer's conduct, with regard to the continued use of antitoxin under the discouraging conditions we have sketched, stamps him as a great member of his humanitarian profession, whose only purpose was the relief of suffering and the cure of disease, without any thought, moreover, of self-glorification. The use of antitoxin has made the necessity for intubation occur much less frequently than before, and thus has undone some of the good contemplated by Dr. O'Dwyer, but has accomplished it in a way which he eminently approved and helped on as far as lay in his power, even at the time when others were doubtful, not without good reasons, as to the results that were being obtained from the use of antitoxin.