COLLECTING 



Planarians are, in general, negatively phototactic animals, hiding in 

 daytime in dark places. They may be collected by examining the under- 

 sides of flat stones and other objects (fallen leaves, pieces of wood 

 etc.) or the stems of submerged or partially submerged water plants. 

 The planarians are then removed from the substrate with a soft paint- 

 brush or the moistened ball of a finger (carefully, without exerting 

 any pressure), placing them immediately in a jar containing water taken 

 from the same habitat. Where there is dense vegetation or an accumu- 

 lation of leaf litter or other debris, samples of these may be taken in 

 a glass jar filled with water; after keeping the jar in a cool place, 

 usually overnight, planarians, if present, will tend to accumulate in 

 the upper layer of the water and may be collected with a wide-mouthed 

 syringe fitted with a rubber bulb. Many planarian species can be 

 attracted by bait (a piece of liver, meat, a dead frog, fish, crushed 

 snails or earthworms) placed under a flat stone and examined after 

 several hours. A very effective method is that of placing the bait in 

 a glass or plastic jar with a lid bearing many small round perforations 

 (of 3-5 mm diameter). The jar is then submerged in a shaded location in 

 a stream, pond, or lake and left for some time. Upon retrieval, usually 

 after 24 hours, planarians will be found inside the jar while larger scav- 

 engers, such as crayfish, have been kept out. This method is applicable 

 also in lakes at greater depths if the bait jar is submerged, together 



Fig. 1. Baiting of planarians in 

 lakes, ba, canvas bag with stones; 

 fl, float; j, jar with perforated 

 lid containing bait. 



with some anchoring ballast, and attached by a line to a float (Fig. 1). 

 Not all planarian species will be attracted to dead bait. Some species. 



