202 THE GROUSE IN HEALTH AND IN DISEASE 



worm is some 20 mm. in length, the female twice as long ; they are 

 extremely thin, and resemble short lengths of very fine white silk. 



Like other members of the family Trichotrachelidse the anterior 

 end of the Grouse whipworm, for about one-fifth of the whole body- 

 length, is narrowed like the lash of a whip. The males are much rarer 

 than the females, and seem to occur, as far as our experience goes, in 

 the proportions of about one to from seven to ten of the females. The 

 eggs, which are very characteristic of the family, do not segment in 

 the body of the female ; in fact, no egg of this species has been seen 

 segmenting. Like the eggs of other members of the family they 

 probably do not develop until they get into water or damp earth. 

 They probably pass directly into the bird, without the mediation of 

 any secondary host, and they infect it at a very early date. They have 

 been found in Grouse-chicks only two weeks old. 



This worm does not seem to be associated with any grave disease, 

 though where it is present there is a great destruction of the epithelial 

 cells lining the duodenum. Masses of epithelial cells, singly and 

 in clumps, are found in the fluid contents of the intestine, and these 

 can hardly be due to post-mortem digestion, as we find them in birds 

 opened immediately after death. 



(iv.) Fam. ASCARID^E. 

 XV, Heterakis papillosa (Bloch). 



Stossich mentions this round worm, as occurring in the Grouse. 

 It is a very common parasite in poultry and pheasants. We have not 

 yet met any examples of it in wild Grouse, but it has occurred in 

 hand-reared birds. 



(v.) Fam. FILARIIDJE. 

 XVI. Filaria smithi. 



Dr Sambon has described under the above name, a " microfilaria " 

 or larval form of some species of Filaria in the blood of Grouse. The 

 adult forms of such larvae usually live in the lymphatics and subcutane- 

 ous tissues ; their larvae pass into the blood, and are conveyed to new 

 hosts by some blood-sucking insects. 



PROTOZOA. 



The great group of Protozoa, or unicellular, animals contains 

 many parasitic forms which give rise to the most dangerous 

 diseases. Sleeping sickness and malaria in man, biliary fever 

 in horses, Texas fever in cattle, Coccidiosis in rabbits, Micro- 

 sposriidois in bees, are evidence of this. Although already some 



