172 Lectures on Bacteria. [f xiii. 



impure water have long been clearly established. It is natural, 

 therefore, as in the previous case, to suppose that a facultative 

 pa'rasite is the proximate cause of the disease. As early as 1871 

 von Recklinghausen found Bacteria, and especially colonies of 

 Micrococcus, in the bodies of those who had died of this fever. 

 Later investigations, given at length in Gaffky's publication (73), 

 have resulted in reports of the occurrence of Bacteria and Fungi 

 which do not always agree with one another. Gaffky has recently 

 undertaken a thorough investigation of the subject, and has found 

 in the internal organs, the mesenteric glands, spleen, liver, and 

 kidneys of persons who have died of typhoid fever, as an almost 

 constant phenomenon — in twenty-six out of twenty-eight cases, — 

 a well-characterised endosporous Bacillus, and always the same 

 kind. This species grows in characteristic form and abundantly 

 on gelatine and blood-serum, and on potatoes exposed to the air. 

 Gaffky, whose work should be consulted, states that in shape 

 it is not unlike Bacillus Amylobacter (see page 100), but con- 

 siderably smaller in size; each rod is about 2-5 ft in length, and 

 the breadth is about one-third of the length. Contrary to the 

 expectations which were justified by the imfailing and character- 

 istic presence of the Bacteria in the bodies of the dead, Gaffky's 

 extensive experiments in the infection of animals, and among 

 them of monkeys, gave wholly negative results. The question 

 of cause must therefore be considered to be at present undecided. 

 How far more recent accounts of successful experiments of this 

 kind will avail to alter this judgment I am not yet able to deter- 

 mine. It has also not yet been proved that the BaciUi of typhoid 

 fever occur spontaneously outside the organism, especially in 

 the water for drinking and for domestic use which is connected 

 with epidemics of the fever. 



II. We are indebted to L6ffler(74) for extended and careful 

 investigations into the nature of diphtheria. His work contains 

 a detailed discussion of the statements of his predecessors, and 

 should therefore be consulted. One well-known and character- 

 istic symptom of diphtheria in the human subject is the forma- 



