from the material so obtained valuable, and in many cases new information was gained. An interesting collection of over six hundred Grouse skins has been prepared, showing the types of plumage found in both sexes at different times of the year and in different districts, and also certain abnormalities. Selections from this collection and from the other material collected by the Committee were exhibited at a soirée of the Royal Society in May 1909, and at the Vienna Sports Exhibition of 1910.
The Committee began their observations in the field in the autumn of 1905; during this season and 1906 the stock of Grouse both in Scotland and England was remarkably healthy, and an excellent opportunity was thus given to study the bird under normal conditions. The Field Observer visited many moors, his visits extending over a period of seven months, from April to October. During this time he got into close touch with the Committee's correspondents in different parts of the country, checked their information, and with their assistance studied the varying conditions governing particular districts. Whenever a case of suspected "Grouse Disease" was reported the moor was visited by the Field Observer or one of his assistants, and specimens of suspicious birds were subjected to laboratory examination.
During 1907 a considerable mortality amongst the Grouse in certain districts was reported in the spring and early summer months. The Committee's experts made a very careful investigation into every case reported, but, contrary to expectation, it was not found that the character of the disease differed materially in its essential features from those occasional isolated cases of mortality which had occurred in the previous year. The Committee found no examples of the acute or sudden form of disease which had been described by former observers. The outbreak of mortality, however, gave an excellent opportunity for collecting data regarding the lingering or pining form of disease which has since been traced to the ravages of the threadworm Trichostrongylus pergracilis.[1]
By 1908 the Committee had completed the preliminary work required to enable the subject to be developed on scientific lines. Evidence and statistics had been collected which indicated the special directions in which further investigations were necessary or likely to be helpful. The natural history of the normal healthy Grouse had been fully studied, and the general pathological characteristics of "Grouse
- ↑ In the following chapters this worm is usually called Trichostrongylus pergracilis, but some writers have preserved Strongylus pergracilis, it is also at times called the Strongyle or the Strongyle worm. A synonym and a list of allied species are given by Dr Shipley on pp. 207 et seq.
