322 DE NOVO ORIGIN OF BACTERIA 



is very poor natural drainage owing to the low-lying situation of 

 the city, and the soil in very many parts is foul and saturated with 

 decomposing organic fluids. The main cause in Dublin and in 

 other cities of these epidemics of typhoid fever is, Sir Charles 

 Cameron thinks, to be found in these very impure states of the soil. 

 He says he has carefully investigated the subject and is "convinced 

 that typhoid fever is often caused by underground air entering our 

 dwellings " from such polluted soils. 



Some years since I received a letter from Dr. Angus Mackintosh," 

 then medical officer of health of Chesterfield, in which, as a result 

 of his experience, he professed his strong belief in the de novo 

 origin of typhoid fever. He said : " If not, how can those who 

 believe otherwise explain the mystery that enteric fever decreases 

 in proportion as the sanitary condition of any district is improved, 

 and that as a direct consequence and in every case ... I say, 

 from a lengthened experience in one of the most fever-stricken 

 districts in England, and after carefully investigating 500 cases 

 of that disease, in my capacity of medical officer of health, that 

 90 per cent, of these could not be traced by me or anybody else to 

 a previous enteric case. The sanitary authority for which I act 

 have borrowed ;^ioo,ooo from the Loan Commissioners during the 

 last four years for drainage works and water-supply, and by altera- 

 tions and arrangements in regard to these important items they 

 have reduced enteric fever already in the district to a very small 

 proportion indeed." 



The moral would seem to be that purity of soil is almost as 

 important as purity of air or water ; that bad drainage may 

 pollute both air and water ; and that some cases of non-specific 

 faecal contamination of the latter — and not only pollution by 

 typhoid dejections — may act as causes of typhoid fever. I feel 

 assured that these are safer and sounder doctrines than the 

 narrower views promulgated by ultra-contagionists. 



If we look to another disease or rather group of morbid 

 conditions — namely, Pulmonary Phthisis and Tuberculous Affections 

 of other organs and parts — a group so common and fatal as to 

 constitute one of the scourges of the human race — there is room 

 for the same uncertainty as to the proportional limits between 

 their de now origin and their spread by means of contagion, 



" Letter dated August 26, 1876. 



