THE LARGE ROUND WORM. 

 AscARis LUMBRicoiDES, Linn. 



Plate XXI. 



Description.— Male and female 150""" each ; in tlie specimens figured 120 each. Body 

 very large and thick, obtuse at each end, of a yellowish cohir, skin marked by rings. 

 The site of the vulva is marked by a smooth wide baud about one-third the entire 

 length from the head. There are three longitudinal bands ; the two wider are nearly 

 lateral ; the third is ventral. The head end is abruptly terminated in three well- 

 formed lips ; the dorsal possesses two papill.e near its base and the two ventral one 

 each. Each lip consists of a chitinous support covered by cuticular membrane. The 

 tail of each is obtuse. The description after Schneider (Monographie d. Nematoden, 

 p. 36) is as follows : 



" Lips nearly equal, their form changing from semi-circular to quadrangular. Teel h 

 very tine. The lobes undivided. The azygos lobe has a rounded point, and reaches 

 with its anterior end to the front of the saddle. Cuticular rings longitudinally ribbed , 

 Vulva 40 to 6.J™'" from the cephalic end. Vagina 11'"™ long. Tail of the male flatoii' 

 the ventral side. Only behind the anus is the skin broadened into a bursa; sixty-nine 

 to seventy-five papillfo on each side ; the first seven pairs of these papilhe stand behind 

 the anus ; the second pair stand nearer tne ventral line than The first and third ; the 

 fourth and fifth pairs and the sixth and seventh pairs are united into double papilliB. 

 (See Fig. 7.) The succeeding stand first in a single row, then in pairs forming a 

 double row ; and on the whole they are very irregular. An unpaired papilhe stands 

 in front of the anus. Spicula two, each a single tube, with its point terminating 

 bluntly and irregularly in front. 



"This parasite occurs in the small intestine in man and swine, and sometimes 

 forces its way into the gall ducts, stomach, cesophagus, nose, and lungs." 



lu one flock of sbeep only lias the author found this parasite. In this 

 flock it occurred in six animals, a majority of those examined. That it 

 is not a common parasite is attested by the writings of various Earo- 

 peau helmiuthologists. A few of the latter have described a special 

 species {Ascaris ovis), from the sheep, but as it is infrequently found it 

 seems to be an inconstant parasite or an adventitious one, i. e., it is 

 probably a constant jjarasite of some other domesticated animal, and 

 occasionally only becomes parasitic on sheep. Besides, the specimens 

 figured always seem to have been immature, and do not differ from 

 Ascaris lumbricoides of the same size and age. 



In the single flock in which this worm was observed all the specimens 

 found were'immature. The vegetative organs of these specimens differ 

 in no essential point from those of Ascaris lumbricoides as figured by 

 various authorities. In addition, a close comparison of these specimens 



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