DENDROCCELUM LACTEUM (Miiller) 



Material. Live specimens of D. lacteum should be kept 

 in a small aquarium with clean water with a few algae and several 

 dead leaves at the bottom. They will live a considerable time 

 if fed on daphnids, copepods and small dipterous larvae. This 

 species is much better for study than Phagocata gracilis, but 

 is rarer and for that reason must be collected considerably be- 

 forehand. The best method of fixation for in toto mounts or 

 cross-sections is hot sublimate (saturated aqueous solution) 

 poured suddenly into the dish in which the animal has been 

 allowed to creep on a dead leaf. If after fixation the animal still 

 adheres to the leaf, it can be sectioned with it; but usually it 

 will let go without losing the ciliated epithelium as is invariably 

 the case when it is fixed in a glass beaker without a dead leaf. 

 Specimens with a well-filled alimentary canal should be mounted 

 in toto, without stain of any kind. The differentiation of in- 

 ternal organs in Planarians is impossible even with Alumcarmin 

 which gives such wonderful results in flukes and tapeworms. 

 The internal anatomy, with the single exception of the digestive 

 organs, must therefore be studied on serial sections. If possible, 

 every student should get a complete series of sections and find 

 those among them which are mentioned below. 



Descriptive Part 



Dendroccelum lacteum is a hermaphroditic fresh-water Tur- 

 bellarian (Planarian), common both in Europe and this country. 

 The body is strongly flattened dorso-ventrally. The mouth 

 opens on the ventral surface considerably behind the middle of 

 the body, and still farther behind lies the joint opening of the 



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