340 



THE BIOLOGY OF STENTOR 



because one can return to a source year after year and find the 

 same species of Stentor. 



Returning to the laboratory, the Hds are removed from the cans 

 to expose them to the air. They are left to stand for half a day but 

 no longer. In this time the stentors will swim to the top. If allowed 

 to stand longer an injurious putrefaction may set in, or worms and 

 water fleas may take their toll, for stentors do not appear to be a 

 dominant form like parameciaor hypotrichs, and persisting cultures 

 are usually not obtained by simply letting the samples stand. After 

 a few hours, stentors, if present, will be found near the surface 

 where they are gathered by pipetting along the miniscus and 

 agitating the floating vegetation and debris. A scraping action with 

 the tip of the pipette when water is being sucked up will serve to 

 loosen stentors which have become attached. This material is 



Fig. 96. Equipment for culturing stentors. 



