ORGANISMS WHICH PRODUCE DISEASE 77 



tuberculosis costs the latter country between $150,000,000 and 

 $200,000,000 yearly ! 



It is not merely by the death-rate that the damage to the 

 community can be estimated. Thousands are annually 

 weakened and maimed by the disease, and incapacitated for 

 work. Pulmonary forms of the disease attack especially those 

 at the wage-earning period of life, whilst surgical forms in 

 bones and joints permanently cripple and disfigure multitudes 

 of children for the rest of their lives, which are often cut short 

 at an early period. 



It is only within the last few years that the public has 

 begun to realise the awful danger to which it is exposed by 

 the prevalence of a disease which can be to a large extent prevented 

 "by the proper education of the people in such matters, and by 

 efficient legislation. Such legislation is urgently required, 

 especially in connection with the milk- and meat-supply, proper 

 housing and sanitation, the improvement of workshops, etc. 

 (especially where dust is liable to be inhaled by workmen such 

 as grinders, stone-cutters, quarrymen, and miners to name 

 only a few), and the prevention of the spread of the disease 

 from man to man, e.g. by spitting in the streets and else- 

 where, and in many other ways. Tubercle bacilli may retain 

 their power of producing disease for many months in dried 

 sputum. Heating at 100 C. for an hour may not kill the 

 organisms if dry. In a fluid such as milk, it takes some 

 fifteen to twenty minutes to kill them at a temperature 

 of 60, and, unless the heating is performed in a closed vessel, 

 many may escape in the cooler pellicle on the surface of the 

 fluid next the air. Actual boiling at 100 C. usually kills them 

 in five minutes. Five per cent, carbolic added to sputum may 

 take as long as twenty-four hours to penetrate and kill the 

 bacilli. Corrosive sublimate, from its property of coagulating 

 the surface of such material, is not a suitable disinfectant, lysol 

 being a much more efficient agent, as it acts upon and dissolves 

 the sputum, and so reaches and destroys the bacteria. 



Infection is carried by the cough of the consumptive, as well 

 as by contaminated dishes and the like. The chief methods 

 of spread have already been discussed at some length in 

 Chapter VI. 



The Tubercle bacillus, which was discovered by Koch in 1882, 

 is a minute rod-shaped organism (see Frontispiece, fig. 12). 

 It often shows a slight curve, and this appearance may be 

 accentuated by the fact that the bacilli may remain united 

 end to end, at a slight angle to one another. They are also 

 often found in little sheaf -like groups or masses, and the in- 

 dividual bacilli frequently show numerous little granules along 



