136 THE STORY OF GERM LIFE. 



produces is the result of the absorption of the 



poisons secreted in the intestines. 



It is but a step from this to the true, parasites. 



Typhoid fever \ for example, is a disease produced 



by bacteria which grow in the intestines, but 

 which also invade the tissues 

 more extensively than the 

 cholera germs (Fig. 30). They 

 do not invade the body gen- 

 erally, however, but become 

 somewhat localized in special 

 glands like the liver, the 

 spleen, etc. Even here they 

 do not appear to find a very 

 favourable condition, for they 

 do- not grow extensively in 

 these places. They are likely 

 to be found in the spleen in 

 small groups or centres, but 

 stained, showing the not generally distributed 



SSsttsS throu S h u il - Wherever they 

 to show the flageiia. grow they produce poison, 

 which has been called typho 

 toxine, and it is this poison chiefly which gives 

 rise to the fever. 



Quite a considerable number of the patho- 

 genic germs are, like the typhoid bacillus, more 

 or less confined to special places. Instead of 

 distributing themselves through the body after 

 they find entrance, they are restricted to special 

 organs. The most common example of a para- 

 site of this sort is the tuberculosis bacillus, the 

 cause of consumption, scrofula, white swelling, 

 lupus, etc. (Fig. 31). Although this bacillus is 

 very common and is able to attack almost any 

 organ in the body, it is usually very restricted in 



