INTERNAL PARASITES 95 



nates itself, after whicli the eggs are devel()i)ed. As soon as 

 the segment is tilled witli full developed or mature eggs, the 

 segment detaehes itself, passes out with the feces and falls to 

 the ground. Thus, at times, we may find in the excrement 

 of an infested bird the segments, white in color and possess- 

 ing the power of movement ; that is, it contracts and expands, 

 showing it to be nliv(\ This is especially noticeable if the seg- 

 ments be placed in water. Before it is detached each segment 

 absorbs its own nutrients through its integument. This nutri- 

 ent consists of the food eaten and digested by its host as 

 alluded to above. New segments are constantly developed by 

 the neck of the tapeworm, growing down, becoming ripe, i. e., 

 filled with mature eggs, and detached ; if not interfered with, 

 this process goes on almost indefinitely. 



Upon disintegration of the segments shed from the worm, 

 and passed out with the feces, the eggs become scattered. The 

 life history of the worm from this state is not well understood. 

 It probably has an intermediate host, by which the eggs are 

 taken up, and within which they pass through a cystic stage 

 and form larvae, which reach the intestine of the bird, become 

 attached and develop to the adult stage. 



The larva consists of a head with its fixation apparatus, 

 namely, the suckers and booklets, if such be present in the 

 adult, and a neck. Having attached itself to the mucous 

 membrane of the intestines, it now absorbs digested food and 

 begins to develop segments, which in a few Aveeks begin again 

 to be shed at intervals, containing fully developed eggs, which 

 number several hundred in each segment. Under proper con- 

 ditions, each egg is capable of producing a single tapeworm as 

 before. 



Tapeworms of Domestic Fowls 



Intermediate host 

 Name Host (cysticercoid stage) 



Davainea proglottina Fowl Slug (Llmax cinereus) 



Davainea tetragona Fowl Snail (Helix) 



Choanota Infundibuliformis Fowl Fly ( Musca domestica) 



Dicranotaenia sphenoides Fowl Fly (Musca domestica) 



Echinocotylus rosseteri Fowl Earth worm ( Lumbricales) 



Duck Fresh water crustacean 



(cypriscinereus) 



Dicranotaenia coronula Duck Cypris cinerea 



Drepanidotaenia gracilis Duck Cypris cinerea 



Duck Cypris viriens 



Drepanidotaenia tenuirostris Duck Cyclops agilis 



Davainea echinobothrida Fowl Not known 



Davainea cesticillus Fowl Xot known 



Hymenolepis carioca Fowl Not known ' 



Davainea echinobothrida Turkey.. Not known 



