738 MODE OF SPEEAD OF INFECTIVE DISEASES. 



Erysipelas and other human infective diseases of 

 wounds (puerperal fever, &c.) : secretions of wounds 

 either in the fresh state or dried on linen, dressings, 

 bedding, ultimately beneath the floors. In the majority 

 of cases we do not as yet know how long the infec- 

 tive agents retain their vitality in the dry state. The 

 ordinary pyogenic organisms are present in dust, on 

 clothing, on the surface of the human body, &c. 



b. Contagious Facultative Parasites. 



Anthrax : 1. The fresh secretions of wounds or of the 

 diseased mucous membranes, also dressings, clothes, &c. 

 2. Fasces of animals suffering from intestinal anthrax, 

 soil and grass impregnated with such dejecta. 3. Pre- 

 served portions of anthrax cadavers (skin, hair), earth 

 (or portions of the dwelling, clothing, &c.) which has 

 come in contact with the blood, organs, &c., during the 

 post-mortem examination. In all cases the duration of 

 the infective power depends on whether or not spores 

 are formed. There are plenty of opportunities for their 

 formation outside the living body in a great variety 

 of substrata, provided the temperature is sufficient. 

 4. Saprophytic colonies of bacilli growing on the banks 

 of rivers, &c. 



Typhoid fever : dejecta of patients. For the most 

 part the infective agents are present in the spore form ; 

 they retain their vitality for a considerable time in a dry 

 state, at all events up to three months (Gafl'ky) ; they 

 also live for several months in watery fluids, and in 

 drinking water. Hence various objects (linen, bedding) 

 which come in contact with the dejecta may retain in- 

 fective properties for a long time. It is probable also 

 that the spores may be preserved for a long time in 

 the soil (in garden and field earth on which dejecta has 

 been deposited). Multiplication can ultimately occur in 

 nutrient materials, especially in milk, in broth, on 

 meat, &c. 



Cholera : dejecta of the sick. They only retain their 



