202 BACTERIOLOGY. 



if the tubercle bacteria themselves were in- 

 herited. As a matter of fact only the predisposi- 

 tion to tuberculosis is really inherited. A. 

 Gartner obtained eggs which contained tubercle 

 bacteria only in the case of intra-abdominal ex- 

 perimental tuberculosis of female canaries. 

 The infection of birds' eggs corresponds, how- 

 ever, to a placental infection in mammals and 

 not to the infection of a mammalian egg. The 

 conveyance of these bacteria into the ovum by 

 means of the semen does not take place ; but, in 

 cases of tuberculosis of the male sexual organs 

 an infection of the female sexual organs may 

 result and a placental infection of the foetus 

 follow in its track. 



In the outside world the bacteria are found, 

 according to Cornet, only where sputum has 

 been deposited in great quantities, as in the 

 sick-room, while in the open the sun soon de- 

 stroys them, so that they have been found out 

 of doors only once, and then (by Schnirer) in 

 dust adhering to grapes. 



In leprosy Armauer Hansen discovered rods 

 which behave toward stains like the tubercle 

 bacteria, but are somewhat more pointed in 

 shape. They are found with special frequency 

 in the skin, where they are enclosed in large 

 cells (Fig. 25 C), which were earlier described 

 by Virchow as lepra-cells. Attempts to cul- 



