2l6 THE ROUND WORMS. 



muscle pains. In the diagnosis we should try to obtain specimens of 

 the pork which has caused the trouble in order to examine for encysted 

 Trichinae. During the diarrhceal stage we may examine the stools for 

 adult worms. In particular examine the blood for eosinophilia. 



STRONG YLID.E. 



In this family the male has a caudal bursa, a prehensile sort of 

 expansion at the posterior end for copulatory purposes. 



Eustrongylus gigas. This is the largest round worm infecting 

 man; it is usually found in the pelvis of the kidney. There seem to be 

 12 authentic cases of infection in man. The females are about 40 

 inches long and about 1/3 of an inch in breadth. The copulatory 

 bursa of the male distinguishes it from Ascaris. The source of in- 

 fection is unknown. The very characteristic ova, with gouged-out 

 oval depressions, may be found in the urine. 



Trichostrongylus instabilis. This is a small strongyle formerly 

 known as Strongylus subtilis. The male is about 1/6 of an inch long, 

 and the female about 1/4 of an inch. It has been found in the upper 

 part of the small intestine of inhabitants of Egypt and Japan. It does 

 not appear to produce symptoms. 



Agchylostoma duodenale. The hook-worm, so called for the 

 hook-like projections of the head dorsally, is probably the most impor- 

 tant of the animal parasites. This specimen in Europe and Africa and 

 the Necator americanus in the new world cause an immense amount of 

 invaliding. The Egyptian anaemia and the Porto Rican anaemia are 

 caused by this parasite. Hook-worms may be found in the small 

 intestine of man in enormous numbers. They either produce their 

 effects by feeding on the mucosa or by causing loss of blood. The 

 males are little than more 1/3 of an inch long and the females little 

 more than 1/2 inch in length. The male can readily be distinguished 

 by his umbrella-like expansion or copulatory bursa. The tail of the 

 female is pointed. The mouth of the Old World hook-worm has 4 claw- 

 like teeth on the ventral side of the buccal cavity and 2 on the dorsal 

 aspect. In N. americanus the ventral teeth are replaced by chitinous 

 plates. The copulatory bursa of the N. americanus is also different, 



