LIFE HISTORY OF TWO RARE CILIATES 369 



Maupas found bouillon, prepared by boiling a minute quan- 

 tity of flour in water, a satisfactory medium for the cultivation 

 of infusoria. A modification of this method was adopted for 

 the cultivation of Halteria, but owing to the rapid fermentation 

 of the flour solution it proved unsatisfactory. After experi- 

 menting with hay-infusions of various strengths, with tap-water 

 and with pond-water, the latter was chosen as the best medium 

 for the cultivation of Halteria stock. The Actinobolus stock 

 *was kept in Syracuse watch-glasses containing pond-water to 

 which had been added a small quantity of Halteria. 



Four lines were isolated on October 18, 1911, as subcultures 

 from Professor Calkins' cultures. The same method was em- 

 ployed as for Spathidium culture, Halteria replacing the Col- 

 pidium as food. Both living and fixed material consisting of 

 total preparations and sections were studied. Schaudinn's fluid, 

 a mixture of 80 parts corrosive sublimate and 20 parts absolute 

 alcohol, was found to be a most satisfactory fixing agent. The 

 method used in making preparations and sections was the same 

 as that described for Spathidium. Many attempts were made 

 to get satisfactory permanent preparations of the tentacles. 

 Narcotizing with chloral hydrate, killing in Schaudinn's mixture 

 and staining for several hours in either picro-carmine or magenta 

 gave fairly good results. Useful, though not permanent, prepa- 

 rations were obtained by killing in osmic acid vapor and mount- 

 ing in glycerine. Living material, however, proved far more 

 satisfactory for the study of these organs than any of the fixed 

 preparations described. 



3. Morphology and physiology 



Actinobolus radians, a holotrichous ciliate, belonging to the 

 suborder Gymnostomina, family Enchelinidae, is a small, almost 

 spherical organism found in fresh water. The average length 

 and diameter of twenty-five individuals measured are 5S.5ij. 

 and 46.8ju respectively (fig. 39). Regarding the shape of the 

 body Entz and von Erlanger disagree, Entz describing the anter- 

 ior as the broader region, Erlanger stating that this portion 



