28 



BRANCH VKKMKS. 



FIG. 



Trichl'na spira'lis. 



Migrating in muscles. Encysted. 



(Greatly magnified.') 



as is often done with ham and Bologna sausage, encysted 



worms are taken into the alimentary tract, where the 



digestive fluids break the cysts, and 

 free the animals, which deposit a 

 multitude of eggs. These eggs soon 

 hatch, and the young TrichinaB work 

 their way through the tissues and 

 migrate to nearly every part of the 

 body ; but finally settle down and 

 become encysted in the muscles, in 

 capsules about fo of an inch long, 

 where they remain indefinitely. If 

 the host can endure the irritation 

 produced by this migration, fatal 

 results will not follow. 

 The Hair-worms, which are found in damp soil and 



in stagnant water, are forms closely 



allied to the Trichina. The Gordius 



(gor'di us) often resembles a long 



hair from a horse's mane, and being 



found in the water, is considered by 



the ignorant to be an animated hair, 



which will finally develop into an eel. The young of 



Hair-worms are often found parasitic in small aquatic 



animals. 



CLASS ANNELIDA (an nel'i da). 



This class includes the higher developed segmented 

 Vermes : the Earth-worms, Sea-worms, and Leeches. The 

 body is elongated, and traversed for its entire length by 

 the alimentary tract. The nervous system consists of a 

 brain proper, placed over the oc.sophaguH (the anterior por- 

 tion of the alimentary tract), round which, on each side, 



FIG. 39. 





Gdr'ffi Us a quat'\ cue. 

 Hair-worm. 



