THE A UTUMNAL DISEASE 49 



two to three weeks, those mice (80 per cent) which 

 had survived the first inoculation with the autumnal 

 microbe, with virulent culture of the spring microbe 

 — tested on control mice — and found that they proved 

 refractory, neither disease nor death ensuing. 



These experiments seem to me at any rate 

 indicative of a means of discovering a protective 

 vaccine for the grouse, i.e. a material which would 

 only produce a transitory illness without fatal result. 

 For if cultures of the autumnal microbe became still 

 more attenuated, say by certain age of the sub-culture, 

 it might be found just of the sufficient degree of 

 activity to cause slight disease, transitory in character, 

 but protective against infection with the fatal dis- 

 ease. To ascertain this a long series of experiments 

 would be required, which I have not had leisure to 

 make. I have myself made some experiments with 

 the gelatine sub-cultures of the autumnal microbe ; 

 these sub-cultures were one week old, ^nd were 

 inoculated into mice, but though the animals showed 

 slight illness, no fatal result followed ; and I can quite 

 imagine that if such or similar cultures were tried 

 by inoculation on young grouse on the moors, — a not 

 at all impossible proceeding considering that most 

 keepers know of most of the grouse nests, — it might 

 be possible to produce a slight transitory illness, 

 protective of the fatal disease. But this is a 



