ROUND WORMS. 



163 



but they are so exceedingly rare as to be only interesting to the 

 naturalist, and are therefore of no practical importance. 



The BOUND-WORM (Ascaris marginata), which a good deal 

 resembles the common garden-worm, varies from four to seven 

 inches in length, the male being much smaller than the female. It 

 is, as may be gathered from its prefix, round, firm, and of ^a pale 

 pink colour, its two extremities, which are alike, being pointed, but 

 slightly flattened. It is found either alone, see (a), or in a group, 

 as shown in the engraving (6), which was drawn from a knot of 



Round Worms. 



worms as actually expelled from the dog. I have already 

 alluded to one peculiarity attaching to its generation, but there 

 are several other points of great interest to the physiologist 



