THE BIOLOGY OF MICROBES, ETC. 



151 



also present in the ova. Numbers of this mic- 

 robe are seen moving backwards and forwards 

 in the blood, etc., of larva? attacked with the 

 disease. Leptothrix forms of the microbe are 

 common when the dis- 

 ease is in rapid progress ; 

 these sometimes measure 

 250 p in length (Fig. 

 35). In the juices of 

 the larval bee during life 

 these bacilli do not pro- 

 duce spores, although 

 after death spores abound. 

 In test-tube cultivations 

 the bacilli grow both on 

 the surf ace of the gelatine 1 

 and along the needle- 

 track. At the surface 

 the bacilli form a delicate 

 ramifying growth, and 

 along the track whitish 

 irregular - shaped masses 

 appear, which slowly in- 

 crease in size and run 

 together. In a few days 



processes are seen to shoot out from these masses, 

 which may extend through the gelatine for long 

 distances from the track, being thickened at various 

 parts, and clubbed at the ends. If only a very few 

 bacilli are introduced with the needle, a beautiful 

 and characteristic growth is obtained, for by this 



i The best growth in gelatine is obtained at about 20 C. 



FIG. 36. BACILLUS ALVEI. 

 (Cheshire and Cheyne,) 



