11 



Roundworms — The Nemathelminth.es 



This phylum of worms includes those with a rounded body in con- 

 trast to the flattened body of the previous phylum, so they are commonly 

 called the roundworms. The phylum name is derived from words mean- 

 ing "thread worms" and, because of their long slender bodies, many of 

 the smaller ones do closely resemble thread. They are among the most 

 abundant of all animals, and there is hardly a spot on the earth that does 



Courtesy General Biological Supply House 



Fig. 11.1. Vinegar eels. These tiny roundworms are are often found in the scum that 



forms on vinegar. We have all, no doubt, eaten some of them in salads seasoned with 



vinegar, but, fortunately, they are not harmful in any way. 



not contain roundworms. A little debris taken from the bottom of a 

 pond will likely contain hundreds of tiny roundworms which can be seen 

 under the microscope threshing around vigorously and apparently get- 

 ting nowhere. Amoeba and paramecium cultures usually contain some 

 of these and it is sometimes difficult to draw a student's attention away 

 from these interesting creatures to study the protozoa. A spadeful of 

 garden soil may contain millions of them ; but, again, the aid of a micro- 

 scope is needed to see them because of their small size. If you like 



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