V THE AUTUMNAL DISEASE 47 



in these cases the disease, though present, was of the 

 sporadic character. If this be the correct view, it 

 would point to the danger existing on such moors, as 

 far as they themselves as well as their neighbours 

 are concerned, and it would explain at the same time 

 how, by lingering on during the winter, an epidemic 

 outburst of the disease may occur in the following 

 spring. Though I do not think that this is the only 

 way in which the spring epidemic may arise, it is at 

 any rate one very probable way. It has been pointed 

 out already, and will be again referred to, that the 

 vitality of the microbe, as proved by experiments with 

 cultures,, is of a very high degree, and it is quite pos- 

 sible that the microbes left in a moor from a previous BatXl*' u**^ 

 epidemic, and remaining sheltered in the soil under .;, 



the heather, grass, or otherwise, may on a future 

 occasion give rise to infection, and thus start a new 

 epidemic. But the theory that cases of a previous 

 spring and summer epidemic linger on through the 

 autumn and winter as sporadic cases in any one part 

 of a district, would furnish a more direct cause for 

 an epidem.ic in the ensuing spring than the other 

 condition, which supposes that the microbes derived 

 from birds that died in the spring or summer may 

 retain their vitality, and remain alive on the moors 

 through the autumn and winter till the next spring, 

 when they might give rise to fresh outbreaks. 



