COLLECTION, CULTIVATION, OBSERVATION 887 



9 parts of 0.5% NaCl and 1 part of human blood serum. Incubation 

 at 10-15°C. 



E. invadens. — Ratcliffe and Geiman (1938) used a mixture of 

 gastric mucin 0.3 gm., "ground alum" salt 0.5 gm., and distilled 

 water 100 cc. About 2 mg. of sterile rice starch is added to each cul- 

 ture tube at the time of inoculation. Culture at 20-30° C. and sub- 

 culture every 7 days. 



E. histolytica and other amoebae of man. — The first successful cul- 

 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. 



CaCl 2 0.2 gm. 



KC1 0.4 gm. 



NaHCC-3 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 sterile in- 

 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 



