128 Phylum Protozoa 



A CULTURE METHOD FOR PARAMECIUM MULTIMI- 

 CRONUCLEATUM AND OXYTRICHA FALLAX 



A. C. Geese, Stanford University 



BOTH of these may be grown in 0.1% lettuce infusion. The lettuce 

 for this infusion is obtained by drying lettuce leaves in an oven and 

 pulverizing. The proper weight of lettuce is boiled in 0.005 M. KH 2 P0 4 

 solution for 3 minutes, after which the infusion is titrated to a pH of 7.0 

 with NaOH. The particles of lettuce may be left in or removed. The 

 culture lasts longer if the particles remain. Usually 15 cc. of such an 

 infusion was seeded with 20 to 100 Paramecia or Oxytrichae. It is quite 

 satisfactory for rough work to use tap water instead of the buffer solu- 

 tion. 



Order heterotrichida 

 Family plagiotomidae 



THE CULTIVATION OF NYCTOTHERUS OVALIS AND 

 ENDAMOEBA BLATTAE* 



Nyctotherus ovalis from the hindgut of the cockroach, Blattella 

 germanica, may easily be cultured in a modified Smith and Barret ( 1928) 

 medium. This medium was used by the discoverers for Endamoeba 

 (Entamoeba) thomsoni, and according to Lucas (1928) it is suitable for 

 the cultivation of neither Endamoeba blattae nor N. ovalis. The medium 

 used by Smith and Barret consists of 19 parts of 0.5% NaCl to 1 part of 

 inactivated human blood serum. By substituting non-inactivated rabbit 

 serum for the human serum a medium is produced in which N. ovalis lives 

 and multiplies freely. Dividing forms are common, and occasionally 

 precystic and cystic forms are met with. Three cultures have been main- 

 tained for 40 days and at the last examination the organisms were as 

 normal in appearance as those found in their native habitat. Sub- 

 culturing is done at weekly intervals, and the cultures are maintained at 

 room temperature. 



The cultivation of E. blattae has been less successful than that of 

 N. ovalis. Two cultures out of twelve attempts were maintained for 29 

 days. At the end of this time the organisms were few in number but 

 entirely normal in appearance and movement. One 2- and one 8-nucleate 

 form were seen, the latter with nuclei of different sizes and evidently pre- 

 cystic. The next examination was negative. This gradual dwindling in 

 number does not necessarily indicate an unfavorable environment, but 



* Reprinted with slight changes from an article in Science 76:237, 1932, by Harry E. 

 Balch, University of California. 



