Pulmonary consumption is relatively more frequent among the poorer than the well to do people, this is partly due to the meagre and scanty food of the poorer, and that they are obliged to subsist almost exclusively on vegetable diet. The higher the meat prices rise and the less the majority of the people can afford to procure meat, the larger will be the number of consumptives. The poorly nourished offer a good soil for the tubercle bacilli in consequence of their weakness. The tissue offers little or no resistance to the growth of the bacilli, these propagate and destroy the powerless and yielding organism with fearful rapidity.
The frequency of pulmonary consumption increases with the size of the cities, or, which is the same, with the number of proletarians. Extreme hunger and want are less frequent in the country than in the city.
That the climate has an important influence on the appearance of pulmonary consumption has long been known. In certain elevated regions this disease seldom or never appears. This experience has been attained in Switzerland and many other mountain regions. Furthermore the Plateaux of Peru and Mexico are considered free from consumption, but also lowlands like Iceland, the Kirgheez steppes and the interior of Egypt are known to be exempt.
Damp and windy climate, especially with very high temperature, or abrupt changes in the temperature promotes consumption; on the other hand it is less frequent in the more moderated climates, especially if they are dry.
Now when the tubercle bacilli have settled in the lungs, they cause various symptoms. One of the most frequent is cough. In the beginning of the disease a short, clear but light, very often dry cough appears. During the further development of pulmonary consumption the cough becomes more periodic; it appears early after awaking, in the afternoon after dinner, and evenings at lying down; it may disappear entirely in the meantime or may be light only; but then as a rule it is no longer dry, but may be attended by expectorations of a varied nature.
Section of a tuberculous knot in the lungs, in which two cavities are seen filled with numerous bacilli. The bacilli distinctly appear as dark lines as a result of the coloring. Enlargement 900.
Tubercle bacilli, Enlargement 2000.
To the left bacilli without spores, to the right bacilli with colorless sections which are thought to be spores.