Parasites of the Kidneys and Vicinity. 457 



STRONGYLUS GIGAS. EUSTRONGYLUS VISCERALIS. GIANT 

 STRONGLE. 



This largest of the round worms makes its internal habitat 

 mainly in the urinary organs or immediately adjacent parts, but 

 has been found in other internal organs as well. 



Distribution. It is widely distributed in the Old World and 

 the New, and probably no country can be held to be entirely free 

 from it. It is most common near the sea coasts, rivers and lakes. 



Hosts. This parasite preys on a wide range of victims includ- 

 ing man, horse, ox, dog, wolf, mink, martin, otter, seal. 



Characters. This worm is white or red, of nearly uniform 

 thickness but tapering toward the extremities, finelj' striated 

 transversely, and with several raised, longitudinal bands : mouth 

 terminal, triangular, with 6 papillae. Male 13 to 40 cm. long : 

 4 to 6 mm. thick, with blunt tail having a terminal, saucer-.shaped, 

 ribless membrane, and single spiculum. Female 7 to 39 inches 

 long : 5 to 12 mm. thick, with obtuse, curved tail, and vulva near 

 the mouth. Oviparous. Ova brownish, 68 to 80 /u. long by 40 to 

 43 /x broad. 



Development. Segmentation takes place in the egg before it is 

 laid, but hatching out of the embryo only occurs after laying 

 when the egg is in contact with water or damp earth. The un- 

 hatched egg may be a, whole year in the cold without losing its 

 vitality. When hatched the embryo is easily killed by drying, 

 and may early perish in pure water though living well in albu- 

 minous fluids. It is cylindrical, thick in front and tapering be- 

 hind, having a conical head and terminal mouth furnished with a 

 protractile, chitinous dart, evidently intended to perforate its in- 

 termediate host. What that host is is still unknown, though its 

 presence as a mature worm in fish-eating animals suggests a fish 

 or aquatic animal as the probable bearer. Schneider has even 

 found an Eustrongylus larva (Filaria Cystica) encysted in fishes. 

 Balbiani, however, failed to hatch the ova of Strongylus Gigas in 

 the alimentary canal of various fishes, in snakes, tritons, river 

 prawns or dogs. 



Strongylus Gigas in the Dog. A variety of different organs 

 may be infested but the urinary organs and especially the pelvis 

 of the kidney are the most common seats of the worm. In a 

 number of cases in which the parasite was found elsewhere there 



