[89] The value of antitoxin treatment in diphtheria is discussed in the _Brit. Med. Jour._, 1899, pp. 197 and 268, by E. W. Goodall, M.D. [90] A detailed study of tuberculosis from its pathological and bacteriological aspect will be found in _La Tuberculose et son Bacille_, pt. i., Straus, Professeur à la Faculté de Médecine de Paris. [91] For differences of virulence between these conditions of pulmonary tubercle see Lingard, _Local Government Board Report_, 1888, p. 462. [92] _Centralblatt. f. Bact. und Parasit._, vol. vii., p. 9. [93] _Animal Tuberculosis_, p. 129. [94] See the _Harben Lectures_, November, 1898, by Sir Richard Thorne Thorne, Medical Officer to the Local Government Board; also the _Report of the Royal Commission on Tuberculosis_, 1896-98. [95] 1. Tuberculosis is a disease mainly affecting the lungs (_consumption_, _decline_, _phthisis_) of young adults and the bowels of infants (_tabes mesenterica_). It may affect any part of the body, and its manifestations are very various. It also affects animals, particularly cattle, by whom it may be transmitted to man. 2. _Its direct cause_ is a microscopic vegetable cell, known as the _Bacillus tuberculosis_, discovered by Koch in 1882. This fungus requires to be magnified some hundreds of times before it can even be seen. When it gains entrance to the weakened body it sets up the disease, which is an _infectious_ disease, though different in degree to the infectiousness of, say, measles. 3. _Trade influence and occupation_, in some cases, undoubtedly predispose the individual to tubercle. Cramped attitudes, exposure to dampness or cold, ill ventilation, and exposure to inhalation of dust of various kinds, all act in this way. In support of the evil effect of each of these four conditions much evidence could he produced. 4. _Overcrowding_ has a definite influence in propagating tubercular diseases. The agricultural counties without big towns, like Worcestershire, Herefordshire, Buckinghamshire, and Rutland, are the counties having the lowest mortality from tuberculosis; whilst the crowded populations in Northumberland, South Wales, Lancashire, London, and the West Riding suffer most. Speaking more particularly, the overcrowded areas of London, such as St. Giles', Strand, Holborn, and Central London generally, show very high tubercular death-rates.