" Of the sequelae of diphtheria, paralysis is by far the most important. This can be experimentally produced in animals by the inoculation of the toxic material produced by the bacilli. [This is the active principle in the antitoxin. Author's note] The paralysis occurs in a variable proportion of the cases, ranging from 10 to 15 and even to 20 per cent. It is strictly a sequel of the disease [of the disease treated with antitoxin?--Author's note], coming on usually in the second or third week of convalescence. . . . It may follow very mild cases; indeed, the local lesion may be so trifling that the onset of the paralysis alone calls attention to the true nature of the disease. . . . "The disease is a toxic neuritis, due to the absorption of the poison. . . . "Of the local paralysis the most common is that which affects the palate. . . . Of other local forms perhaps the most common are paralysis of the eye muscles. . . . Heart symptoms are not uncommon. . . . Heart-failure and fatal syncope (death) may occur at the height of the disease or during convalescence, even as late as the sixth or seventh week after apparent recovery." It appears to me that the mystery of these "sequelae" can easily be explained. It is certain that a mere "sore throat," not serious enough to be diagnosed as diphtheria, cannot produce paralysis or heart-failure; but we know positively that the antitoxin can do it and does do it. The cases that Dr. Osler refers to undoubtedly received the antitoxin treatment, because it is administered on the slightest suspicion of diphtheria, nay, even to perfectly healthy persons "for purposes of immunization." Then is it not most likely that these "mysterious after-effects" are caused rather by the highly poisonous antitoxin than by the "sore throat?" In my own practice, I am frequently consulted by chronic patients whose troubles date back to diphtheria "cured" by antitoxin. Among these I have met with several cases of idiocy and insanity, with many cases of partial paralysis, infantile paralysis, and nervous disorders of a most serious nature, also with various other forms of chronic destructive diseases. In the iris of the eye, the effect of the antitoxin on the system shows as a darkening of the color. In many instances, the formerly blue or light-brown iris assumes an ashy-gray or brownish-gray hue.