DISEASE AND ITS CAUSES 



403 



importance of the various diseases to which grouse are subject. The findings here presented 

 are necessarily limited in scope by time and resources. While progress has been made, much 

 is left for future study before all the important questions can be answered. 



Realizing the necessity for this research, the Investigation's study of disease was initiated 

 in 1931 and has been continued to date, thus permitting observations over a period of eleven 

 years. During that time, 1,728 adult grouse and 1,119 chicks have been collected for autopsy. 

 The birds were taken from all parts of the State, 50 of the 55 counties outside of New York 

 City and Long Island being represented. 



Table 62 illustrates the distribution of the collections by regions and years. The regions 

 here considered, Adirondack. Catskill and Rest of State, are the same as is used in other 

 chapters of the Report (figure 13 I. 



TABLE 62. THE NUMBER OF ADULT GROUSE AND OF GROUSE CHICKS 

 COLLECTED FOR PATHOLOGICAL EXAMINATION 

 BY YEARS AND REGIONS 



Three separate pathologists examined the material collected during their respective assign- 

 ments. This fact, together with changes in the methods and techniques employed as experi- 

 ence accumulated, occasionally raise difficulty in evaluating results. Therefore, in carrying 

 out certain comparisons, it was considered advisable to limit analyses to records of autopsies 

 made by the present authors or under their supervision. 



DISEASE AND ITS CAUSES 



It is definitely known that most birds and mammals play host to many plant and animal 

 parasites. It is not equally understood, however, that only a few of these really damage the 

 animals in which they live. \^Tien they do, it is at their own risk. In effect, these disease- 

 producing agents may actually be committing suicide if their activities seriously impair the 

 hosts' well-being. It is erroneous to apply the term "disease"" to the presence of parasites which 

 are causing no alteration in the function or structure of their host. 



It should be borne in mind that disease is not an entity which enters the body from without 

 but is a process of abnormal activity of certain bodily functions in response to an injury. This 

 process mav or may not be associated with ap])reciable changes in body structure. However, 



