136 BACTERIOLOGY. 



The fact that tubercular sputum preserves its 

 virulence for several months, even after desicca- 

 tion, has been attributed to the 

 formation of spores, and Babes 

 has drawn attention to ovoid 

 grains in old cultivations of the 

 bacilli, which he succeeded in 

 staining red, while the bacilli 

 FlG - 6l - were stained blue. 



BACTERIUM OF CHICKEN- j h j definition o f spirilla 

 CHOLERA, FROM BLOOD 



OF INFECTED HEN, x Zopf gives the spore-formation 



as absent or unknown. In 



comma-bacilli in sewage water, the author has often 



noted appearances very suggestive of refractive 







4? 0** 



** /^\ 



^ * 5? 



FIG. 62. FIG. 63. 



BACTERIUM OF CHICKEN-CHOLERA, COMMA BACILLI IN SEWAGE 



FROM MUSCLE JUICE OF AN IN- WATER, STAINED WITH 



FECTED HEN, x 2500 [from a GENTIAN VIOLET, x 1200. 

 photograph]. 



spores (Fig. 63). The same also may be observed 

 in vibrios, differing by their regular contour from 

 the irregular spaces occasionally observed in stained 

 preparations (Figs. 64 and 65). They are possibly 

 only vacuoles. 



Respiration and nutrition. Like all a-chlo- 

 rophyllous vegetables, bacteria require for their 

 nutrition oxygen, nitrogen, carbon, water, and 

 certain mineral salts. Many require free access to 

 oxygen, others can derive it from the oxidised 



