ASCARIS LUMBRICOIDES Linnaeus varietas 



SUILLA 



Material. A. suilla is so common in pigs that it may be 

 found in great quantities at any slaughterhouse. The specimens 

 should be placed directly into Perenyi's fixing fluid in which they 

 may remain for any length of time. Material thus fixed is good 

 both for dissection and microscopic anatomy. Sections should 

 be stained in haematoxylin and eosin. Every student should 

 receive one male, one female, a cross-section showing the nervous 

 ring and a cross-section through the middle of the worm. 



Descriptive Part 



Ascaris suilla is a common parasite of the pig and is closely 

 related to the human round worm. It is a typical representative 

 of the Class Nematoda. 



External features. Ascaris suilla has the shape of a long 

 cylinder attenuated at both ends. At one end is the mouth 

 surrounded by three finely toothed triangular lips, one of which 

 is dorsal and the other two ventro-lateral in position. Extend- 

 ing practically through the whole length of the animal are four 

 equidistant lines: a median -ventral line, a median dorsal line, and 

 two lateral lines. About two millimeters from the anterior end 

 is a small excretory pore in the median ventral line. The posterior 

 end of the female is practically straight and the anus appears as a 

 transverse slit with two -anal lips on the ventral side about two 

 millimeters in front of the tail end. The female genital opening 

 is also median and ventral in position and is situated about one- 

 third the entire length from the head. The position of the 

 opening in younger females is nearer the middle of the body. 



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