Amoebidae 87 



necessary in this case to keep the organism in culture over any long 

 period of time. 



The second purpose is to preserve a constant supply of culture mate- 

 rial over long periods for animal inoculation, metabolism experiments, or 

 immunological studies. Therefore a medium which may be successful 

 for the first purpose may be entirely unsatisfactory for the second. With 

 this in mind we will give a brief discussion of the following media: Boeck 

 and Drbohlav (1925), Dobell and Laidlaw (1926), Kofoid and Wagener 

 (1925), Tanabe and Chiba (1928), Cleveland and Collier (1930), Craig 

 (1930), Deschiens (1930), St. John (1932). 



Of these, the first three have been so well tested that there is little 

 need of discussing them further. They are all satisfactory in maintain- 

 ing cultures over long periods of time. We prefer the L. E. A. medium 

 of Boeck and Drbohlav to their L. E. S. medium. We feel, however, 

 that the growth of Blastocystis and bacteria is less in the L. E. B. 

 medium of Kofoid and Wagener (1925). Particularly is this noticeable 

 in the culture of Dientamoeba jragilis. We have found, too, that the 

 optimum pH for Dientamoeba is lower than for Endamoeba histolytica 

 (about pH.6.6). 



Of the others we have found that St. John's medium is excellent in 

 producing a sudden increase in rate of multiplication and is thus useful 

 for classroom studies as well as for diagnostic purposes. It has also the 

 advantage of being relatively inexpensive and easy to prepare. But we 

 have never been able to keep the amoebae in this medium longer than 

 several weeks. 



St. John, 1932. 



SLANTS LIQUID 



None Heart muscle (Bacto Beef Heart Dehydrated) is extracted 



in a modified Locke's solution by boiling for one hour. 



Heart muscle i gram 



Locke's solution * iooo cc. 



The extract is filtered through filter paper and auto- 

 claved at 15 lbs. pressure. "Ralston's" whole wheat 

 flour is added. 



Craig's media (as he himself states) are primarily to aid the diagnos- 

 tician, and not for the maintenance of cultures by transfer. 



♦Locke's solution: 



Sodium chloride 9.00 gm. 



Calcium chloride 0.24 gm. 



Potassium chloride 0.42 gm. 



Sodium bicarbonate 0.20 gm. 



Dextrose 2.50 gm. 



Distilled water 1000 cc. 



