OBSEliVATIONS ON A FLAGELLATE OF CblliCOMONAS. 243 



cultures of this flagellate tree from other Protozoa for about 

 a year, and it is only that circanirstances preventing ine from 

 continuing these observations I now describe what results I 

 have already obtained. 



Method of Observation. 



I have found the best liquid culture medium to be hay 

 infusion to which a small quantity of faeces has been added. 

 The flagellates will live and multiply in hay infusion alone, 

 but, as in other thin media, the numbers of" flagellates are 

 always very small, so that any observation is difiicult to make. 

 In the thicker medium the numbers are not only larger but the 

 movements of the flagellates are slower and accordingly more 

 easily followed. For keeping stock cultures small test-tubes 

 were used as in bacteriological methods, but for making- 

 observations hanging-drops in the moist chambers of Max 

 Schultze were most useful. In these hanging-drop prepara- 

 tions the flagellates would live for weeks, till finally, all nutri- 

 ment being used up, encystment followed. By the addition 

 of fresh nutriment to the hanging-drop the culture would 

 commence again. 



In addition to the liquid medium I have found the solid 

 agar medium used for the culture of amcebae most useful. It 

 was first employed for the culture of flagellates by Berliner. 

 This observer, working with Copromonas major, found 

 that on the solid medium the flagellates multiplied rapidly 

 till enormous numbers were present. I can fully confirm 

 this, and for the study of the details of nuclear division 

 the presence of such lai-ge numbers of dividing forms is 

 very useful. The medium I employed differed slightly from 

 that used by Berliner. For the culture of amoebae I have 

 used with success the medium first invented by Musgrave 

 and Clegg, and I have found it equally good for the flagel- 

 lates at present under discussion. I have employed it in 

 the ordinary Petri dishes. By unveiling the dishes the 

 progress of the culture may be watched under the low 

 powers of the microscope. A very useful method for the 



