Lavender now estimates that there are between 25,000 and 50,000 pellagrins in the United States.

The disease appeared in Italy about 1750, but was first described there in 1771 by Frapolli, of Milan, who applied the name "pellagra" (Italian pelle, skin, and agra, rough). Marzari in 1810 first called attention to the relation between maize and pellagra. In 1844 Balardini suggested the theory that the disease might be due to spoiled maize, that is, maize which had undergone fermentative change by reason of the growth of fungi on the grain. At present pellagra is most prevalent in northern and central Italy and in Roumania. Triller states that in 1906 there were 30,000 pellagrins in Roumania; in certain parts of Italy as much as 30 to 50 per cent. of the population have the disease; in 1899 there were nearly 73,000 sick with the disease in all Italy, this being upward of 10 per thousand of the rural population. The disease also occurs in Spain, Corfu, Asia Minor, Austria, Servia, Bulgaria, and occasionally in India, Africa, Barbadoes, Mexico, South America, and Egypt.

As preventive measures must be based entirely upon our conception of the etiology of the disease, it is necessary to consider briefly some of the views upon this subject. It is the accepted opinion of most students of the disease that pellagra is an intoxication due to using Indian corn (maize) as a food, which, under the influence of some parasitic growth (bacteria or fungus), has undergone certain changes with a production of one or more toxic substances. Lombroso, who studied this subject for years, made alcoholic and watery extracts from spoiled maize and obtained chemical substances of an undetermined nature, which were given to men and animals with the production of symptoms analogous to pellagra. The interpretation of all such work is as yet, however, in an uncertain state.

With regard to the parasites found on maize, it may be said that the varieties are numerous, and no single one seems to be constant enough to be rated as the definite causative agent. Seni incriminates the Aspergillus fumigatus as the cause of the maniacal form of pellagra, and the Aspergillus flavescens as the cause of the depressive form. These molds have resisting spores which withstand heat, hence ordinary cooking is not sufficient to destroy them. The Bacterium maydis has also been associated with the disease. Lombroso, as a result of his studies, maintained that pellagra is due to a poison (toxine) developed in maize by microorganisms (molds or bacteria), in themselves harmless to man (that is, saprophytes).

Other views concerning the nature of pellagra are: that it is an autointoxication, the poisonous substances being produced in the bowels as a result of the constant and almost exclusive diet of corn, which produces certain changes in the intestinal flora, and the production of poisonous

substances. A somewhat similar view is that the disease is an intestinal mycosis, the offending microorganisms being eaten with corn and colonizing in the intestinal tract. Others regard the disease as of an infectious nature, and several parasites have been reported in the blood and organs. In France especially the idea has been brought forward that pellagra is not a definite morbid entity at all, but a symptomcomplex sometimes observed in alcoholics and cachectic states of diverse origin, the erythema being regarded only as a common solar erythema. Sambon, as the result of epidemiological studies, brought forward (1905 and again recently) the view that pellagra is an insect-borne disease, and incriminates the Simulium reptans.

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Raubitschek recently brings forward evidence that pellagra depends upon some noxious substance (noxe) activated by the action of sunlight. This is the photodynamic theory, and corresponds to the action of light upon a photographic negative. It is suggestive that the skin lesions in pellagra are mainly confined to the exposed surfaces. There is also a substance in buckwheat poisoning (fugopyrismus) that affects animals exposed to the light, but not those kept in the dark.

Pellagra usually runs a chronic course, with acute exacerbations, which usually occur in the spring and fall of the year. The disease sometimes runs an acute and rapidly fatal course. The development seems to be more rapid and grave in children. The poison, whatever its nature, produces toxic and trophic manifestations. The triad of symptoms are: (1) digestive disturbances, (2) erythema, and (3) nervous disturbances. The final scene usually includes profound cachexia, great muscular weakness, and insanity.

CORN.-Maize or Indian corn is a native of the Western Hemisphere and was cultivated by most of the northern and western tribes of North American Indians before Columbus reached these shores. The importance of the corn crop to-day may be gathered from the fact that, according to the census of 1900, almost one-third of all the land under cultivation in the United States was devoted to corn. It was grown on 88.6 per cent. of all the farms in the country in the crop for 1889. The value of the annual crop now exceeds a billion dollars. Corn contains 24.7 per cent. of water. The water-free material consists of 12.7 per cent. proteins, 4.3 per cent. fat, 79.3 per cent. starch, sugar, etc., 2 per cent. crude fiber, and 1.7 per cent. of mineral matters. The several nutrient substances in corn and other common cereals are much the same; the individual compounds, however, making up these groups differ considerably.

The kernel or seed, it must be remembered, is not inert, but a living thing which, under favorable conditions, will develop into a new plant, and each part of it is made up of cells especially fitted for a particu1 Berliner klin. Wochens., Vol. XXIII, No. 26, June, 1910.

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lar rôle in this process of reproduction. Roughly speaking, a seed consists of three divisions: the skin, the germ, and the endosperm. It is a well-known fact that corn, when allowed to ripen before it is taken from the stalk, keeps much better than immature corn. It is certain that protective substances (antibodies) are developed in the kernel which retard the growth of bacteria and molds. Moist corn kept warm spoils readily, whereas corn once thoroughly dried is proof against serious fermentative changes.

The tests for spoiled corn are not entirely satisfactory. They may be divided into physical, biological, and chemical tests. The physical test consists mainly in the luster, the absence of molds, the odor, and taste. The biological test consists in planting the corn; from 90 to 95 per cent. should germinate. The chemical test includes among other determinations the proportion of ash after burning, and Gosio's phenolic reaction with ferric chlorid. A green purple color with this reagent indicates fermentation, with the production of phenolic compounds.

Spoiled corn may be renovated by polishing and then heating, to prevent further growth of molds. It is difficult to detect renovated corn by inspection alone, but the biological test will disclose whether or not it has been heated. The practice of renovating corn should either be prohibited or be placed under strict official control.

There are three hundred or more varieties of corn. It is quite practicable to raise corn either with a high protein content or a high fat content. Smith, at the Illinois Agricultural Experiment Station, in ten generations raised the oil or fat content from a minimum of 4.7 per cent. to a maximum of 7.337 per cent. Such corn is sought after for the fattening of hogs. While of advantage to hogs, it may be detrimental to man, for when corn becomes moldy it is always the embryo that is affected first, and there the fungus flourishes best. According to Alsberg, the greater part of the toxic material is in the decayed embryo. It happens that the greater part of the oil is also located in the embryo. The variety rich in oil is probably also one with a large germ. It is, therefore, possible that corn with a large embryo and high fat content may spoil more readily and produce a greater amount of the poison responsible for pellagra.

It should be borne in mind that, while corn itself may not be the direct cause of pellagra, it may hold the same relation to that disease that the swamps bear to malaria.

PREVENTION. The line along which pellagra prophylaxis is planned depends entirely upon our conception of the disease. As pellagra prevails among the poor, especially those who live under uncleanly and squalid conditions, it at once becomes evident that economic and social improvements are an important part of the program. Prophylaxis spells prosperity in this disease as in others. The Italian struggle culminated

in the law of 1902 for "the prevention and cure of pellagra," which was inspired by Lombroso's views upon the disease. The Italian measures may be summarized as follows: those aimed at the cure of the disease are a free distribution of salt (a government monopoly in Italy), the distribution of food either at the homes of the patients or through sanitary stations, and the treatment of severe cases in hospitals for pellagrins and in insane asylums. The prophylactic measures are mainly directed against the use of spoiled corn as an article of food. They comprise a census of the disease and a report of all cases; the testing of corn and meal brought in at the frontiers or offered for sale to the mills and the prohibition of its sale if found spoiled; the exchange of good corn for spoiled corn; desiccating plants; cheap coöperative kitchens; the improvement of agriculture; and the education of the people. The corn is inspected by experts and is submitted to certain tests. If found spoiled, its sale for food is prohibited. The tests are not entirely satisfactory from a scientific standpoint, but seem sufficient for practical purposes. According to Mr. Cutting, the weak point in the inspection of corn seems to be in dealing with homegrown corn, especially the meal, either at the mills or on the markets. There seems to be no solution of this difficulty except governmental ownership of the mills. The agricultural improvements are directed toward teaching the use of better varieties of corn and proper methods of culture, handling, etc., or how to supplant corn entirely with a more profitable crop.

The desiccating plants for the artificial drying of corn are considered a very important prophylactic measure, as they prevent the spoiling of the grain. These desiccators are of two types, fixed and portable, and there are a large number of public desiccators throughout Italy. There is also a provision in the law for public storehouses properly constructed, where the grain may be stored under the best conditions to prevent spoiling. Rural bakeries and economic kitchens are establishments where an effort is made to eliminate from the peasant's diet bread made of corn, by supplying good white bread and other food at a low cost. Above all, however, stands the education of the people to the dangers of spoiled corn, and the healthfulness of a varied diet and better living conditions.

The results of the campaign in Italy seem to be a diminution in the amount of the disease in central Italy. Strange as it may seem, however, the disease is increasing its area, and parts of Italy previously free from pellagra are now developing the disease.

SECTION IV

AIR

CHAPTER I

COMPOSITION OF THE AIR

The air constitutes a gaseous ocean in which we live; it consists of a vast volume of gases at least one hundred miles high.' Ordinarily we speak of this gaseous envelope of the earth as the atmosphere, and the water resting upon the surface of the earth as the aquasphere, while the solid structure of the earth is called the petrosphere. Between the atmosphere on one hand and the petrosphere and aquasphere on the other hand is the region of most abundant life, and this is spoken of as the vivosphere.

An abundant supply of fresh air is necessary at all times. The importance of fresh air was almost completely ignored in practical life until recently thanks to the tuberculosis propaganda. While recent studies have shown that the air is not to be feared as a frequent medium for conveying specific infections, it has been demonstrated that an abundant supply of fresh air is necessary to perfect well-being. Statistical studies seem to prove that, of the predisposing causes of sickness which are usually in action, impurities of the air are perhaps the most important. This has been demonstrated over and over again in the case of horses, cattle, and dogs, as well as in men confined in badly ventilated barracks, jails, and other places.

Many other factors are now known to be a greater menace to health than the "bad" air of crowded places; sanitarians, however, have come to regard an abundant supply of pure fresh air, well conditioned, as one of the real essentials for health and maximum efficiency.

Further, it should be remembered that the combustion of the food we eat depends upon the oxygen of the air we breathe, and that diges tion and metabolism are stimulated and improved by an abundant supply of fresh air or rendered sluggish and retarded by prolonged exposure to vitiated air.

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Forty-five or fifty miles is its practical limit, and anything beyond that distance is in an extremely tenuous state.