In 1810, Marzari insisted that the two diseases, pellagra and Alpine scurvy, which had a few years previously been recognized as identical, were caused by the consumption of maize and from this time on the maize theory as to etiology has been supported in Italy. Later on (1872 to 1909) Lombroso elaborated the maize theory of etiology and so strongly presented this view that it is impossible for us lightly to set aside the arguments of this great physician. While the zeists, as the advocates of the maize etiology are termed, insist that pellagra made its appearance in Europe following the introduction of Indian corn, after the voyages of Columbus, there does not seem to be any evidence that pellagra ever existed among the North American Indians. In 1905 Sambon insisted that pellagra was a protozoal disease and in 1910 claimed that it was probably transmitted by a midge, _Simulium reptans_. About 1907 pellagra was found to be an important disease of the Southern States of the United States and since that time the number of cases has steadily increased so that it is now estimated that there have been approximately 200,000 cases in the United States. It is generally conceded that isolated cases of pellagra had occurred in the United States prior to 1907, but they generally were diagnosed differently. =Geographical Distribution.=—In Europe it is most prevalent in Italy, Balkan States, Greece, Turkey, Spain and Portugal. In Roumania there were about 100,000 cases in 1906. The disease has decreased in incidence and virulence in Italy, there having been in 1910 only 33,869 cases, as against 104,607 cases in 1881. The disease was first recognized in Egypt by Sandwith in 1893 and is now known to be widespread in Lower Egypt. It is rare in Upper Egypt where they live on millet instead of maize. It exists in Algiers. It has been reported from India and the Straits Settlements and prevails extensively in the West Indian Islands as well as in Mexico and Central America. The disease in the Southern States of the United States is of a more fatal type than elsewhere, the average mortality having been 39.10%. The death rate in the United States has fallen, thus the rate in Mississippi for the years 1914 to 1916 was only ten per cent. At present the Italian mortality is only about 3% although formerly it was much higher. ETIOLOGY AND EPIDEMIOLOGY =Etiology.=—Like other diseases of unknown etiology the views in this connection are innumerable. _Zeists and Anti-zeists._—It is customary to divide the adherents of the different views as to the cause of the disease into two groups, the zeists, who advocate a connection between maize or Indian corn (_Zea Mays_) and the disease, and the anti-zeists, who claim that corn has nothing to do with pellagra.