208 THE GROUSE IN HEALTH AND IN DISEASE 



"Length of female mostly f inch, sometimes very nearly inch; breadth 

 above the tail -JTTF inch to -z^ inch, narrowing at the extreme point to ^^^ inch ; 

 longitudinal diameter of the eggs -rl^ inch, their breadth being TTSTS inch." 



Eight years later Cobbold described, 1 under the name of S. douglassii, a 

 nematode which occurred in great numbers /n the proventriculus of certain South 

 African ostriches. Their presence was associated by the ostrich-farmers with a 

 certain amount of disease, and with some deaths. 



Finally, we have the species S. quadriradiatus recently described by E. C. 

 Stevenson. It occurred in considerable numbers in the intestines of a flock of 

 fancy pigeons which had been almost destroyed by a malady of unknown origin 

 early in 1904. In his article upon this disease, Stevenson points out that the 

 presence of a few nematodes in the caecum of the pigeon causes little harm. If, 

 however, the threadworms exist in large numbers, disease becomes manifest. 

 This Stevenson attributes to two causes : the first is the loss of blood ; but there is, 

 I think, little or no evidence that these nematodes live on blood. The second 

 cause is the piercing of the walls of the intestine, 5 which permits the bacteria in the 

 contents of the alimentary canal to make their way into the peritoneal cavity, 

 where they set up peritonitis. Evidence is gradually accumulating as to the 

 occurrence of this, and some of the French authorities even think that such a 

 perforation, made as a rule by Trichocephalus trichiurus (dispdr), is one of the 

 more common, if not the most common, causes of appendicitis in man. The presence 

 of these worms further sets up an inflamed, catarrhal condition of the walls of the 

 intestine, which leads to a debilitating diarrhoea and to general disorders of the 

 digestive system. As in other cases, the nematodes doubtless give off toxins, the 

 effect of which is largely confined to the nervous system and to the cells in the 

 blood of the host. 



The genus Trichostrongylus has recently been established by Looss 3 to include 



certain forms which he has separated out from the large genus Strongylus. The 



Strongylus pergracilis of Cobbold corresponds so closely in structure 



with the species described by Looss that I think there can be no doubt 



that it also should be included in the new genus. The suggestion made above 



1 Journal of the Linrusan Society, London, " Zoology," xvi., p. 184, 1883. 



2 An actual perforation of the membrane is not in all cases necessary. There are examples of bacteria 

 traversing the wall or parts of the wall of the alimentary canal which have been locally or temporarily 

 weakened in some way. 



' " Centralblatt fur Bakteriologie, Parasitenkunde," xxxix., p. 409, 1905. 



