AVES 



439 



only be determined by competent investigation. That was 

 well shown in the grouse epidemic of 1872. In that epizooty 

 the greater number of the birds succumbed to the injuries 

 produced by a nematode worm (Strongylus per gracilis, Fig. 73), 



FIG. 73. Strongylus pergracilis. a, Head and neck; b, c, d, e, tail of the male in various 

 positions ; f, til of the female ; g, section showing termination of the oviducts ; h, three 

 eggs. Highly magnified. Original, 



but, without doubt, the occasional presence of numerous tape- 

 worms (Tcenia calva) hastened the consequent fatality. The 

 following table, giving the results of examination of twelve 

 diseased grouse from the Earl of Cawdor's estate, will show 

 how inconspicuous a part tapeworms played in the epidemic 

 of 1872. For further details I must refer to my brochure on 

 the ' Grouse Disease/ and to some other memoirs quoted in the 

 bibliography below. 



