SPIRILLUM CHOLEIUE ASIATICS. 459 



infection. The more carefully the hands are cleansed 

 and the articles of food prepared, the more will the paths 

 of spread from existing sources of infection be diminished. 

 It is evident that in this respect marked differences must 

 exist between more or less civilised countries ; between 

 new and well-built, and old and narrow cities ; between 

 poor and wealthy neighbourhoods ; between the portion 

 of a city inhabited by the poor and that in which the 

 better class dwell. 



As a special example of the action of general clean- Arrangements 

 liness we have the effect, often confirmed, of a good of water and' 



supply of water and drainage. Formerly these arrange- 

 ments were supposed to produce their good hygienic 

 results chiefly by keeping the soil and ground water free 

 from all putrescible materials, and thus withdrawing the 

 necessary nutrient substrata from any infective germs 

 which may have reached them. This interpretation is 

 no longer sufficient in accordance with our present know- 

 ledge as to the conditions of life of the pathogenic fungi, 

 but the good effects of these arrangements for cleanli- 

 ness still exist as they did formerly, for they lead to 

 marked diminution of the sources of infection and to a 

 limitation of the paths of spread. They act by remov- 

 ing as quickly and completely as possible all the dejecta 

 and the water employed for cleansing linen, utensils, 

 &c., without allowing them to come in contact with the 

 surface of the soil, with wells, &c. ; and further, by pro- 

 viding an ample and convenient supply of water, so that 

 cleanliness in every form is favoured, and thus infection 

 is limited to contact, nutrient materials, and so on. 

 But even with these arrangements we must not under 

 all circumstances expect a complete protection against 

 the spread of cholera, for at certain places and at given 

 times it is evident that other sources and paths of 

 infection may develop, and thus the disease may spread 

 quickly and over a wide area in spite of these sanitary 

 arrangements. 



The mode in which linen is cleansed may be especially cleansing- of 

 referred to as another of the habits of life which has an f thes ' linen ' 

 important influence on the spread of this disease. Koch 



