DICROCCELIUM LANCEATUM Stiles and Hassall 



= Distomum lanceolatum 



Material. D. lanceatum is by far the best species of 

 Trematodes for class study. Although it does not occur in the 

 United States, at least not as an indigenous species, it is pref- 

 erable to other Trematodes on account of the clearness with 

 which all the parts of the complicated reproductive organs may 

 be seen even by the inexperienced student. D. lanceatum is so 

 common in Europe, especially in Germany, that there should be 

 no difficulty in procuring any number of specimens. The best 

 results are obtained, when the specimens have been preserved in 

 a weak formalin solution and stained in alum carmin. Prepared 

 slides of Distomum in toto may be bought of H. Bocker in 

 Wetzlar at the listed catalog price of Mark 1.5 per slide. The 

 lung flukes of frogs used in this country as representative types 

 of Trematodes are far inferior to D. lanceatum, and possess 

 moreover no Laurer's canal. Each student should receive a 

 prepared slide of D. lanceatum stained and mounted in toto and, 

 if possible, a complete series of cross-sections. 



Descriptive Part 



Dicroccelium lanceatum is a typical representative of the 

 Class Trematodes of the Phylum Platyhelminthes. It is the 

 commonest liver fluke of sheep in Europe, found often in hun- 

 dreds in the gall ducts. Its body is quite flattened dorso- 

 ventrally. The anterior end may be recognized by the mouth 

 sucker and the ventral surface by a similar sucker or acetabulnm 

 situated in the median line about one-fifth the animal's length 



62 



