LUMBRICUS TERRESTRIS, L. MuUer 



Material. L. terrestris may be kept alive in moist soil 

 or preserved in Perenyi's fluid for dissection. Specimens for 

 transverse microscopic sections should be fed for several days on 

 milk or olive oil in a jar free from soil and fixed in either Perenyi's 

 or Petrunkevitch's sublimate mixture. Every student should 

 receive one large specimen killed by slow narcotizing in alcohol, 

 and the following transverse sections: through the region of the 

 seventh to tenth segments (oesophagus), through the region 

 between the twentieth to thirtieth segment and through the 

 clitellum. 



L. terrestris has been selected on account of its considerable 

 size. The genus Lumbricus should not be confused with either 

 Eisenia (common species Eisenia fcetida and rosea) or Helodrilus 

 (common species Helodrilus caliginosus, chloroticus) . For dis- 

 tinctive characters see Das Tierreich, Oligochaeta by Michaelsen. 



Descriptive Part 



Lumbricus terrestris is an earthworm equally common in 

 Europe and the United States and a typical representative of the 

 Class Oligochaeta. It is a hermaphrodite like the majority of the 

 species belonging to the same class. 



External anatomy. The body of Lumbricus is segmented 

 externally. The number of segments varies from one hundred 

 and ten to one hundred and eighty, a condition similar to that in 

 Nereis, showing that in this respect the Oligochaets have not yet 

 attained the degree of fixed segmentation found in leeches. The 

 anterior end of the worm is thicker and almost round in a cross- 

 section. The posterior end is distinctly flattened dorso-ventrally. 



