DEVELOPMENT OF PLANTS 163 



compounds, toxins. Among the more terrible of these infec- 

 tious bacteria may be mentioned'those producing consumption. 

 These affect especially the lungs of animals and cause, according 

 to data now available, from 150 to 200 thousand deaths annually 

 in the United States. It is altogether probable with complete 

 returns that the death rate will exceed by 50 thousand the higlier 

 figure mentioned above. Consumption is no longer considered 

 so fatal a disease as formerly. A person of ordinary constitution, 

 if suitably nourished, can be cured by living in the open air. 

 This pest could probably be wiped out witliin ten years, if the 

 habit of spitting could be stopped. The spores and plants are 

 readily carried away in the air from the dried sputum to Ix; 

 inhaled again and so spread the disease. The bacteria causing 

 lockjaw, Of tetanus, are especially abundant in the soil in certain 

 localities. Through wounds they are carried into the s\stem. 

 These forms, like others previously noted, are peculiar in that 

 they can not grow in the presence of oxygen. Conse(juentl\- the 

 dangers of infection are great in deep wounds. An innnediatc 

 cauterization of the entire surface of the wound will kill the or- 

 ganisms. Other well-known bacterial diseases are j^neumonia, 

 diphtheria, erysipelas, Asiatic cholera, t>phoid, and sj)K"nic 

 fevers and grippe. It should be noted that many diseases, 

 as smallpox, malaria, hydrophobia, yellow fever and probably 

 scarlet fever, etc., are due to a low order of microscopic animal 

 life. Disease-producing bacteria are either localized, as in the 

 lungs, throat, intestines, or are generally distributed throughout 

 the system. The symptoms of the disease are largely due to 

 the products of decomposition caused by tlie growth of tlu- bac- 

 teria or by secretions from the bacteria themselves, all of whicli 

 act as poisons and are commonly referred to as toxins. In 

 other cases the toxins are formed by the infected animal owing 

 to the disturbance of its growth and nutrition b\ the bacteria in 

 its tissues. In the same way bacteria are the cause of many 

 diseases among the plants, as in corn, melons, many truits, etc. 

 See Bacteria in Relation to Plant Disease, by Hrwin V. Smith. 



These bacteria are constantly finding their wa\- into our iuKlies 

 by means of the breath but so long as the system is in a ht-althv 



