Ill CHARACTER OF BACILLUS 31 



even under a moderately high power, e.g. under a 

 power of 300 to 400, appear as spherical cocci ; but 

 on examining carefully with oil immersions the 

 marginal parts of the masses, where the individuals 

 are loosely arranged, it is clear that most of them 

 are distinctly oval or even rod-shaped or cylindrical. 



When the microbe is examined in mice or guinea- 

 pigs that have died after inoculation with the culture, 

 it is found that the number of rods and cylindrical 

 forms is very much greater than in the grouse or in 

 the sub-cultures of the grouse. This is well shown 

 in Figs. 10 and 11. 



In the ammer, bunting, greenback, and finch, 

 which are highly susceptible to the disease, many 

 individuals are rod-like or cylindrical ; and also, in 

 the blood of the grouse dead during late summer 

 and autumn, rod-shaped individuals abound. 



Whatever the source of the organism when grown 

 in broth, — or better still, when grown in or on nutri- 

 tive gelatine to which 5 per cent, solid sea salt (Sted- 

 man's sea salt) has been added, — the bacteria grow 

 out into long cylindrical threads, most of them smooth 

 and uniform, but some made up of individual cylin- 

 drical bacilli (see Fig. 12). There can then be no 

 doubt that we have to deal with a form which corre- 

 sponds to those groups of bacterial species known as 

 bacilli. 



