34 THE ROUNDWORMS OF DOMESTIC SWINE. 



however, to warrant the assertion that the parasites occur throughout 

 the middle and southwestern (and probably eastern) United States. 

 Specimens have been collected by Hall in 1908 from a hog kept at 

 Bethesda, Md., in all probability of eastern origin. They have also 

 been collected by Kilborne at Washington, D. C., and by Stiles and 

 Hassall at Benning, D. C. ; in the latter case, however, it is possible 

 that the host animal had been shipped to the local slaughterhouse 

 from a Western or Central State. 



RELATIVE FREQUENCY OF THE TWO SPECIES. 



That Physocephalus sexalatus occurs less abundantly than Arduenna 

 strongylina in American swine is indicated by the following data : 



All the worms contained in a bottle of specimens forwarded from 

 Chicago were sorted out by species and sex. The bottle contained 

 744 specimens. Of these, 599, or approximately 80 per cent, were 

 Arduenna strongylina, and the remaining 145, or 20 per cent, were 

 Physocephalus sexalatus. Of the 599 specimens of Arduenna strongy- 

 lina, 399, or 56 per cent, were females, and 260, or 44 per cent, were 

 males. A smaller percentage of males was found among the speci- 

 mens of Physocephalus sexalatus. Of the 145 specimens found, 69 

 per cent were females and 31 per cent were males. 



LESIONS ASSOCIATED WITH ARDUENNA STRONGYLINA, ARDUEN- 

 NA DENTATA, AND PHYSOCEPHALUS SEXALATUS. 



From an economic standpoint these three species are^probably of 

 considerable importance. Prior to 1899 it was not considered that 

 Arduenna strongylina was especially injurious to swine. Neumann 

 (1892a), in mentioning that Spiroptera strongylina caused small sub- 

 mucous tumors of the stomach and that no morbid disturbances were 

 attributed to it, summed up the general opinion of the time regarding 

 the economic importance of the parasite. More recent reports, 

 however, indicate that these parasites should be regarded as the 

 possible etiology of serious gastric disorders. 



Von Ratz (1899d) found Spiroptera strongylina very common 

 among swine hi Hungary, and attributed to this parasite several 

 epizootics of a rather serious nature, in one of which, out of a herd of 

 230 sows, 21 were seriously affected and 6 died. Some of the symp- 

 toms were described as follows: 



The diseased sows suffered from loss of appetite, eating very little and in the worst 

 cases finally refusing all food; on the other hand, they drank water excessively and 

 were very restless, continually pawing the ground. 



Describing the post-mortem lesions seen in the stomach, Von Ratz 

 says: 



At the pyloric end the mucous membrane was covered with a thick, lamellous, 

 firmly adhering pseudomembrane, which upon being removed revealed a superficial 

 loss of tissue of the mucous membrane. Under the mucous membrane lay numerous 



