3io Scientific Proceedings (116). 



microscope, i.e., before extensive drying of the medium has oc- 

 curred. The characters and appearance of all colonies investi- 

 gated were profoundly modified by a change in this variable. 

 Marked variation from controls over water occurs with the solu- 

 tions used having a water vapor tension of 75 to 85 per cent, 

 relative humidity, thus showing that a relatively slight departure 

 from saturated conditions is of considerable importance in bac- 

 terial surface cultures. 



It might be added that the simple device above described 

 serves excellently for anaerobic plate cultures, with alkaline pyro- 

 gallate solution in place of the dehydrating solutions, dextrose- 

 methylene blue media being easily decolorized and remaining so. 



Abstracts of the Communications, Pacific Coast Branch. 

 Twenty-ninth meeting. 

 Berkeley, California, May 4, IQ21. 

 161 (1743) 



Councilmania lafleuri, a new amoeba of the human intestine. 



By CHARLES ATWOOD KOFOID and OLIVE SWEZY. 



[From the Zoological Laboratory, University of California, and the 

 Bureau of Communicable Diseases, California State Board of Health.] 



There exists some confusion and uncertainty among investi- 

 gators of human intestinal amoebae as to certain features of struc- 

 ture and activities of the non-pathogenic Endamceba coli (Loesch) 

 Schaudinn. The points in debate are its habit of ingesting red 

 blood corpuscles, its mobility in the free state, the existence of 

 more than one type of cyst, the structure and location of the 

 karyosome, the presence of cysts with an irregular number of 

 nuclei (other than 2, 4, 8, 16), and the escape of amcebulae from 

 the cysts in faeces. 



We believe these questions have arisen from the confusion 

 hitherto by investigators, of two species, Endamxba coli and a 

 new one, generically distinct, which we designate as Councilmania 



