io8 



Bulletin 2cco. 



W- ""^v 



In tuberculosis we have similar 

 conditions, but they differ in detail 

 from those in diphtheria in three 

 very important points, — the length 

 of the period of incubation, the way 

 in which the specific bacteria pro- 

 duce the disease, and the time re- 

 quired for the disease to run its 

 course. With diphtheria the speci- 

 fic bacteria produce a toxm which 

 poisons the system, and this toxin 

 is the cause of death. In tubercu- 

 losis, the specific bacteria, do not 

 produce such a toxin, but they live 

 in one or more of the tissues of the 

 body, multiply there, and by their 

 increase penetrate deeper and 

 deeper into the organs of the body, 

 destroying the tissues as they go. 

 Finally the injured organs give rise 

 to symptoms, at first slight, but 

 gradually they become more and 

 more serious until death is pro- 

 duced, because some organ neces- 

 sary for the life of the individual 

 has been destroyed. While diph- 

 theria completes its course in a 

 few days or weeks, tuberculosis re- 

 quires for the same purpose 

 months and more often 

 years. 



It is important that 

 both the specific, and the 

 infectious, nature of bovine 

 tuberculosis should be 

 understood. It is a specific 

 disease because it is pro- 

 duced by a single cause — the 

 tubercle bacillus. It is in- 

 fectious because the tubcr- 



Fici. 128.— I Iw carcass uf an auiiiial killed for cle bacteria, the organisms 

 beef shotviiii^ tuberculosis of the liver, oineiiliDii ,, , , ,, ,. 



and lungs. Generalised tuberculosis (Reynolds) . '^^^^^ produce the disease, 



must first be taken into the 



^v 



