!3o Phylum Protozoa 



Family Halteriidae 

 For the culture of Halteria see pp. ioo and 177. 



Order hypotrichida 

 Family oxytrichidae 



UROLEPTUS MOBILIS* 



THIS organism, appearing in considerable numbers in an old hay 

 infusion that had been standing for several months, was successfully 

 cultivated and abundant material for study of all the important phases 

 of the life history was secured. 



After attempts to cultivate Uroleptus on fresh hay infusion failed, this 

 medium was discarded and boiled flour water, 24 hours old, was sub- 

 stituted. To make this, 150 mg. of white flour is boiled for 10 minutes 

 in 100 cc. of spring water and allowed to stand exposed to the air for 

 24 hours. 



With this medium it was found that the organisms would live and 

 would divide about once in three days. Later, a more satisfactory me- 

 dium was obtained by mixing 2 parts of the flour water, 2 parts of spring 

 water, and 1 part of old hay infusion. This improved medium was used 

 for nearly 3 months, the individuals dividing approximately once a 

 day. Finally a still better medium was obtained by boiling 100 mg. of 

 chopped hay with 130 mg. of flour in 100 cc. of spring water for 10 

 minutes and diluting this, when 24 hours old, with an equal part of fresh 

 spring water. With this medium made fresh every day, the organisms 

 divide from one to three times per day. 



As in previous culture work, a single individual is transferred to about 

 200 mg. of the culture medium contained in a flat, 40-mm. square, ground 

 glass, hollowed dish, 8 mm. in thickness. On the following day the 

 number of individuals is counted and a single individual from these is 

 then isolated and transferred to fresh culture medium made the day be- 

 fore. After an individual is transferred to fresh medium, the remaining 

 individuals are placed in a Syracuse dish containing about 10 cc. of the 

 fresh culture medium. Here they multiply in large numbers, consti- 

 tuting the "stock" material, the source of dividing and conjugating 

 forms. 



M. E. D. 

 References 



For the culture of Oxytricha see p. 64. 



For the culture of Oxytricha jallax see p. 128. 



For the culture of Stylonychia see p. 64. 



♦Abstracted from a paper in /. Exper. Zool. 27:293, 1919, by Gary N. Calkins, 

 Columbia University. 



