CHAPTER VIII 



" GROUSE DISEASE " CONTINUED STRONGYLOSIS l 



PART I. EFFECT OF STRONGYLOSIS ON THE GROUSE 



THE round worm Trichostrongylus pergracilis was first described 

 under the name of Strongylus pergracilis, by Cobbold. 



T, pergracilis is an extremely fine worm, measuring in the 

 male from to f of an inch, and in the female from f to J inch. 

 They are very narrow and hair-like, and, as a rule, whitish in 

 colour, but sometimes have the tinge of blood when seen in a 

 very thin layer on a slide through the microscope. The 

 extremely fine head and neck, finer than the finest needle, 

 readily penetrates into the tissues of the caecal walls. The 

 worms are very transparent, clearly revealing their internal 

 structure, and they are so soft that the pressure of a cover- 

 slip almost always ruptures them. The cuticle is very clearly 

 and definitely ringed, and the rings are so constituted that 

 whilst the worm can easily work its way forward through a 

 tissue, it would have difficulty in wriggling backward. The 

 rings give the edge of the body a strongly serrated appearance 

 like a saw. This is most marked a little way behind the head, 

 and extends over about one-third the body length. There is 

 no trace of longitudinal marking on the cuticle. The general 

 appearance of the worm when seen under the microscope is 

 shown on the accompanying figures, and a detailed description 

 of its anatomy is given in the original Report. 2 



1 The term " Strongylosis " is employed in this chapter to denote the disease caused 

 by Trichostrongylus pergracilis (Cobbold) ; though it would perhaps be more strictly 

 correct to name the disease Trichostrongylosis. 



2 Report, vol. i. pp. 209 et seq. 



206 



