AN INVESTIGATION INTO THE CAUSE OF THE SPONTANE- 

 OUS AGGREGATION OF FLAGELLATES AND INTO THE 

 REACTIONS OF FLAGELLATES TO DISSOLVED OXYGEN. 



Part I. 



By H. MUNRO FOX. 



{From the Laboratory of the Marine Biological Association, Plymouth, England-, and 

 the Biological Laboratory of the School of Medicine, Cairo, Egypt.) 



(Received for publication, September 21, 1920.) 



The Phenomena of Spontaneous Aggregation and Band Formation. 



It is well known that many flagellate and ciliate Protista form 

 spontaneous aggregations. That is, when a drop of water containing 

 the organisms is mounted on a slide for examination under the micro- 

 scope the flagellates or ciliates are frequently seen to collect into 

 clumps or masses. The center of such a collection may be a piece 

 of some solid present in the water, or there may be no such visible 

 focus. It is the second of the two cases that is here termed spontane- 

 ous aggregation, and the present investigation was undertaken with 

 the object of finding out the cause of this phenomenon. The dis- 

 covery of the cause then led on to the more general question of the 

 relation of the organisms to varying amounts of dissolved oxygen. 



Throughout the investigation the same species of flagellate was 

 used; namely, Bodo sulcatus. It was originally described by Mere- 

 schkowsky.^ For the present investigation the flagellate was obtained 

 by taking grass from the garden behind the laboratory at Plymouth 

 and steeping it in tap water. The best material was obtained from 

 6 day old cultures. The flagellates were then most abundant with- 

 out being too much mixed with other organisms. In cultures older 

 than 6 days there were too many bacteria present and, still later 

 on, too many ciliates. 



^ Mereschkowsky, C, Arch. mikr. Anat., 1879, xvi, 153. 



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