56 PROTOZOAN PARASITISM 



surface fluid. The cultures should be incubated at 

 37° C. and transplanted on the second day, when the 

 amoebae are most numerous. 



Kofoid and Wagener (1926) substituted for the 

 human blood serum in this medium rabbit, rat, cat, 

 and guinea pig blood. Their most satisfactory sub- 

 stitution was defibrinated rabbit blood, used 0.5% 

 in Locke's solution. 



Craig (1926) succeeded in growing Endainoeha 

 histolytica in seven parts of 0.85% sodium chloride 

 solution and one part of inactivated human blood 

 serum. 



As Smith and Barret (1928) call to attention, 

 Craig's medium is a variation of a mixture of blood 

 serum which they, or one of them (Barret, 1921; 

 Barret and Yarbrough, 1921 ; Barret and Smith, 1924; 

 Barret and Smith 1926) have used to cultivate Blasto- 

 cystis hominis, Balantidium coli, Endamoeha bar- 

 reti, and Endamoeha ranarum. They suggest that 

 variations of the strength of this simple medium may 

 prove satisfactory for cultivation of a large range of 

 parasitic protozoa. 



The author has used it for more than ten years, 

 along with similar mixtures of pleural and abdominal 

 cavity fluids for cultivating several flagellates, as well 

 as Blastocystis. Some of this work has been pub- 

 lished previously and will be referred to under appro- 

 priate subjects; the first was not reported. 



There appear to be unsolved difficulties in all of 

 these methods of cultivation. In the writer's labora- 



