COLLECTION, CULTIVATION, OBSERVATION 717 



ture was made by Boeck and Drbohlav (1925) who used the follow- 

 ing media. 



(a) Locke-egg-serum (LES) medium. The contents of 4 eggs 

 (washed and dipped in alcohol) are mixed with, and broken in, 50 cc. 

 of Locke's solution in a sterile flask with beads. The solution is made 

 up as follows: 



NaCl 9 gm. 



CaCl2 0.2 gm. 



KCl 0.4 gm. 



NaHCOa 0.2 gm. 



Glucose • 2.5 gm. 



Distilled water 1000 cc. 



The emulsion is now tubed so that when coagulated by heat, there 

 is 1-1.5 inches of slant. These tubes are now slanted and heated at 

 70°C. until the medium becomes solidified. They are then autoclaved 

 for 20 minutes at 15 pounds pressure (temperature must be raised 

 and lowered slowly). After cooling the slant is covered with a mix- 

 ture of 8 parts of sterile Locke's solution and 1 part of sterilean- 

 activated human blood serum. The tubes are next incubated to 

 determine sterility. The culture tubes are inoculated with a small 

 amount of faecal matter containing active trophozoites. Incubation 

 at 37°C. Yorke and Adams (1926) obtained rich cultures by inocu- 

 lating this medium with washed and concentrated cysts of E. his- 

 tolytica in 24 hours. 



(b) Locke-egg-albumin (LEA) medium. The serum in LES medium 

 is replaced by 1% solution of crystallized egg albumin in Locke's 

 solution which has been sterilized by passage through a Berkefeld 

 filter. 



Dobell and Laidlaw (1926) used Ringer's solution instead of 

 Locke's. 



(c) Ringer-egg-serum (RES) or Ringer-egg-albumin (REA) me- 

 dium. Solid medium is the same as that of (a) or (b), but made up in 

 Ringer's solution which is composed of 



NaCl 9 gm. 



KCl 0.2 gm. 



CaCla 0.2 gm. 



Distilled water 1000 cc. 



The covering liquid is serum-Ringer or egg-albumin. The latter is 

 prepared by breaking one egg white in 250 cc. of Ringer's solution 



