156 



ANARTHROPODA 



FlG. 182. Three encysted Trichinae in human flesh. Photograph enlarged sixty 

 diameters. 



harmless to man. A species of Anguillula is also common 

 in stagnant ponds and ditches, and may be found by ex- 

 amining under the low power of the microscope a drop 

 of water scraped from decaying wood or leaves taken from 

 foul water. 



Horse-hair worms of which Gordius aquations is the most 

 common occur in streams, ponds, and watering troughs. 

 They do not originate from a horse hair, as is popularly sup- 

 posed. They are from five to ten inches long and as thick 

 as a pin. The eggs are either laid in the damp earth or 

 water. In the latter case the young socn after hatching 

 bore into the larva of some aquatic insect which is later 

 eaten by a fish. The young hair worm no larger than a 



