COMMUNITY SANITATION 407 



ulated them in earlier centuries are fearful evidence of 

 the low community standards of those days with respect 

 to sanitary conditions. Many of these old cities have 

 passed out of existence or have been replaced by others. 

 When we contemplate the enormity of the various 

 problems relating to food, water, sewage, and health in 

 a large modern city like New York, we must marvel 

 that they are so well solved. Wherever the individual 

 is located he needs fresh air, pure water, wholesome food, 

 shelter, a clean body, and beautiful things to look at. 

 In the large cities his needs are emphasized by his depend- 

 ence on others, and at the same time his obligations 

 are increased because 

 of his close association 

 with others. The city 

 is no longer an accu- 

 mulation of human be- 

 ings, but a highly or- 

 ganized society whose 

 interests are the inter- 



ests Of the State. FIG. 358. Bacteria and the Point of a 



Bacteria. There Cambric Needle ' 



The figure shows the comparative sizes. 

 are millions OI tiny The minute dots at the end of the needle repre- 



livine- nre-anisrrm in sent the size of the bacteria - The others 



arranged around the needle are bacteria more 

 WOrld (Figure 358). highly magnified. The sources of the latter 

 rpn i n i are ( a ) typhoid fever, (6) diphtheria, (c) boils 



Lney are Single-Celled or abscesses, (d) tuberculosis, (e) sour milk, 



bodies and belong to (/) grip - 



the divisions of plants and animals. We have already 

 learned that many one-celled plants are known as bac- 

 teria and belong to the class of fungi. 



Man divides bacteria into good and bad, according to 

 their effect on the things which he wants to keep. Most 

 of the bacteria are useful and valuable such as those 



