to the clinical picture presented by the malady. Most observers of recent cases—which were just beginning to be recognized—believed the process to be a true inflammation. Some regarded the degeneration of the ganglion cells as a sequel to the inflammation, while others looked upon the degeneration and the inflammation as simultaneous processes. Following the lead of Pierre Marie, most considered that the anterior horns were always affected because of implication of the arteria centralis. Wickman, on the other hand, maintained the lymphatic spread of the disease, and the latest experimental researches confirm the correctness of his opinion.
Very inexact ideas were prevalent concerning the nature of the disease until Strümpell and Pierre Marie, from its general character and its onset with fever, recognized it to be an infection. Their opinion was supported by the fact that infantile paralysis sometimes appeared in epidemics.
The first epidemic of infantile paralysis to be described was that reported by the Swedish physician, Bergenholtz, in 1881. Subsequently, several others were recorded, but most of them consisted of relatively few cases. The most celebrated were those which occurred in 1887 and 1895, in Stockholm. They were reported by Medin. Neither in these, nor in any other out-break, however, was it possible to ascertain how the disease spread. During the Swedish epidemic of 1905, through the observation of indisputable abortive forms, and through the study of all possible means of communication, Wickman succeeded in proving that Heine-Medin's disease spreads from person to person in exactly the same way as other contagious maladies. This has, in subsequent epidemics, partly been confirmed by Ed. Müller, P. Krause and others.
Although many problems of this malady have been elucidated, many are still unsolved. The cause of the disease is not yet known. Of late years, quite a number of very interesting experimental investigations of poliomyelitis in monkeys have been published and have greatly increased our knowledge of this disease. Landsteiner and Popper were the first successfully to infect monkeys. From the work of Flexner and Lewis, Landsteiner and Prasek, Knöpfelmacher, Leiner and Von Wiesner, Römer, Römer and Joseph, Levaditi and Landsteiner, Netter and Levaditi, and
