352 MICRO-ORGANISMS AND DISEASE [CHAP. 



several generations the same effect of general tuberculosis is 

 produced as that directly by matter of pulmonary human 

 tuberculosis. 



The tubercle bacilli show definite characters in cultivation. 

 Koch succeeded in cultivating them on solid blood-serum. 

 Inoculating the slanting surface of the solid serum with 

 tubercular matter, and provided no other bacteria are 

 introduced, Koch noticed the first signs of growth in ten to 

 fourteen days. Koch used for inoculations of the serum 

 tubes the tubercular deposits of a swollen lymphatic gland 

 of a guinea-pig, three to four weeks previously inoculated 

 with tubercular matter, clean sterile instruments being used. 

 After ten to fourteen days the first signs of the growth of 

 the tubercle bacilli show themselves in the form of whitish 

 points and patches, resembling dry scales. On further 

 growth they enlarge, and where close together they coalesce 

 into dry whitish scaly masses with irregular outline. From 

 such primary cultures subcultures on serum were then 

 carried out. But under a magnifying glass, or better under 

 the microscope, the growth and multiplication of the 

 tubercle bacilli can be seen already before the end of the first 

 week. Peculiar curved, or convoluted, or S-shaped whitish 

 hues, which prove to be strands of tubercle bacilli, are noticed 

 even at this early stage. On Agar broth the growth is very 

 limited, so also in broth. But Roux and Nocard showed that 

 by adding six per cent, glycerine to Agar meat infusion, 

 or to meat broth, the tubercle bacilli can be brought to rapid 

 and extensive multiplication. On glycerine-Agar-beef broth 

 the tubercle bacilli grow very rapidly, the growth being 

 already visible after six to eight days, and after several 

 weeks covers the whole surface as a whitish, peculiarly 

 wrinkled, dry film (Fig. 137) extending as a pellicle over the 

 condensation water at the bottom of the tube. In order to 



