TUBERCULOSIS 121 



effort of the body to wall off these bacilli produce a 

 reaction as a result of the dissemination throughout the 

 body of the products of the tubercle bacilli. This re- 

 action is expressed in terms of symptoms which make 

 the individual realize that something is wrong. In a 

 comparatively small number of instances this tubercu- 

 lous process becomes chronic, the tubercle bacilli con- 

 tinue to grow, the infected areas become larger and 

 larger, and more and more of the organ in which they 

 are seated becomes destroyed. More and more symp- 

 toms are produced and the efficiency of the body is 

 reduced by the influence of the poisons distributed 

 throughout the body in the circulating blood and by the 

 destruction of part of some organ of the body. In rare 

 instances a tubercle may grow in the wall at a small vein 

 or in a small artery and eventually rupture into the 

 vein, and the contents of the tubercle with many tuber- 

 cle bacilli are thus discharged into the blood stream. 

 When this takes place there is a rapid dissemination of 

 bacilli throughout the body, causing a marked increase 

 in the number of tubercles growing in the body. In 

 such a case the condition known as miliary tubercu- 

 losis is produced. 



HEREDITY. As has been stated, until the time of 

 Villemin the generally accepted theory was that tuber- 

 culosis was hereditary. It is now known that fetal 

 infection may occur but that when such infection oc- 

 curs, the mother is in the advanced stages of tuberculosis 

 and tubercle bacilli are circulating in the blood which 

 passes through the placenta into the fetus. This is a 

 occurrence and in only a few instances have reports 



