H. MUNRO FOX 511 



Work done in the past on chemotropism of flagellates will have 

 to be revised in the light of the above facts, since the oxygen con- 

 tent of solutions used has never been taken into account. 



The work was done during the months of June to September, 

 1919, at the Laboratory of the Marine Biological Association, Ply- 

 mouth. I wish to thank the Director and Staff for the help and 

 advice given to me. I wish also to thank the Trustees of the Ray 

 Lankester Fund for having nominated me to an Investigatorship. 

 Mr. C. Clifford Dobell F.R.S. was kind enough to identify the 

 species and examine fixed preparations for me. 



