324 THE ROUND WORMS 



STRONGYLID.E 



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

 pansion at the posterior end for copulatory purposes. 



The mouth is usually provided with six papillae and at times with a 

 chitinous armature. Those without the chitinous armature are in- 

 cluded in the subfamily Strongylinae (Strongylus, Trichostrongylus) 

 while those having an armed mouth are in the subfamily Sclerosto- 

 minae (Ancylostoma, Necator, Triodontophorus, (Esophagostoma, Phy- 

 saloptera). 



Eustrongylus gigas (Strongylus renalis). This is the largest round 

 worm infecting man; it is usually found in the pelvis of the kidney 

 (giant strongyle). 







Two or more worms may so distend the kidney as to convert it into a mere shell. 

 Pain, haematuria and other symptoms of pyelitis, together with the finding of the 

 eggs, make the diagnosis. There seem to be seven authentic and eight doubtful 

 cases of infection in man. 



The females are about 40 inches (i m.) long and about Y$ inch (8 mm.) in 

 breadth while the male is about 10 inches (25 cm.) long. 



The collar-like copulatory bursa of the male distinguishes it from Ascaris as does 

 also the dark red color. The source of infection is unknown but it has been suggested 

 that the larval stage may exist in fish. 



Many of the reported cases were simply fibrinous clots from ureters or wandering 

 round worms. 



The very characteristic ova, with gouged-out oval depressions, may be found in 

 the urine, and are diagnostically confirmatory. 



Strongylus apri. This nematode is common in the lungs of hogs, producing a 

 bronchitis in young animals but apparently harmless for adult ones. It has been 

 reported once from the lungs of a six-year-old boy. The male is about i inch (25 

 mm.) long with two long spicules. The female is about 2 inches long and has a 

 sharply hooked posterior extremity with the vulva just beyond the bend. The 

 mouth has six lips. The eggs contain embryos when laid. 



Trichostrongylus instabilis. This is a small strongyle formerly known as Stron- 

 gylus subtilis. The male is about % inch (4 mm.) long, and the female about 

 Y inch (6 mm.) Anteriorly it tapers to a pointed head end which is only 

 about one-tenth the thickness of the posterior extremity. The male has a bursa 

 and two prominent equal spicules. It has been found in the upper part of the small 

 intestine of inhabitants of Egypt and Japan. It does not appear to produce symp- 

 toms. Ova like hookworm ones (73 to 90 X 42;*). Ransom gives T. col ubr if or mis 

 as the proper name. It is a common parasite of sheep and goats in the U. S. and 

 may exist in man in such regions. Stiles has kept in mind the possibility of such 

 infections in his Southern States hookworm work but has failed to find cases in 

 man. The eggs are not only larger than hookworm ones but show later stages of 

 segmentation. 



Triodontophorus deminutus. This is a small round worm with three forked teeth 



