"GROUSE DISEASE" 187 



An attempt has been made to work out the distribution of disease in Grouse, 

 both in time and in space, by first collecting records from every possible source, 

 and as far back in time as it is possible to go. Each record is then allocated to 

 its proper position on a map for its own proper year. By having a separate 

 outline map of the British Isles for each year, on which every outbreak and 

 every occurrence of disease is marked in red, it is possible at a glance to 

 arrive at certain conclusions, e.g. : 



1. How the incidence of disease changes from one set of counties or one 

 district in one year to another set of counties or to another district in the next 

 year ; thus the track of the epidemic from year to year can be distinctly followed. 



2. The frequency of disease in each district is seen at a glance, and its rise and 

 fall during the years which intervene between the periodic outbreaks can be 

 followed. 



3. The disease - incidence of each year can be compared with its weather 

 record, and conclusions thus may be drawn regarding the predisposing causes, 

 as well as the method of dissemination. 



4. By combining a large series of annual disease-records on one map an idea 

 is obtained as to which areas suffered most, and whether any areas are 

 disease-free. 



5. Such a combination of annual disease-record maps can be superimposed 

 upon similar maps showing rainfall, watersheds, heights above sea-level, and 

 surface soils or sub-soils, and so it becomes possible to recognise whether disease 

 is in any way connected with one or other set of physical conditions. 1 



" Grouse Disease" has long held the attention of many observers. Sportsmen 

 and naturalists have done much for the field work, but the laboratory work 

 has been less popular. Klein, Cobbold, Farquharson, Colquhoun, p rev i ous 

 Andrew Wilson, and Young have all contributed towards an under- ^T^rouse 

 standing of the pathology of " Grouse Disease," while Macdonald, r)isease -" 

 Macpherson, Stuart-Wortley, Adams, Speedy, Teasdale-Buckell, and a host of 

 other naturalists and sportsmen have supplied a large collection of interesting 

 facts and observations, and an almost equal number of hypotheses and theories 

 to account for them. It will be of use first to discuss the conclusions at which 

 various writers have arrived, and as Klein's work stands out pre-eminently, and 

 includes so great a proportion of what was known about " Grouse Disease" at 

 the time, the simplest course will be to take his conclusions first. 



1 For the results of this l>ranch of the Inquiry, vide vol. ii. Appendix I. 



