COLLECTION, CULTIVATION, OBSERVATION 901 



should be absolutely neutral. Do not use Canada balsam for mount- 

 ing, as acid in it promptly spoils the staining. 



For Wright's stain, fixation is not necessary. With a medicine 

 dropper, cover the dried blood film with drops of undiluted Wright's 

 stain, and let the film stand horizontally for 3-5 minutes ; then the 

 same number of drops of neutral distilled water is added to the stain 

 and the whole is left for 10-30 minutes. The stain is then poured off 

 and the film is rinsed in neutral distilled water. Dry. Mount in xylol 

 and cedar wood oil. 



Use of coverglass on a stained blood film is advocated, since a 

 cedar wood oil mounted slide allows the use of dry objectives which 

 in the hand of an experienced worker would give enough magnifica- 

 tion for species determination of Plasmodium, and which will very 

 clearly reveal any trypanosomes present in the film. Furthermore, 

 the film is protected against scratches, and contamination by many 

 objects which may bring about confusion in detecting looked-for 

 organisms. 



Films made from splenic punctures for Leishmania or Trypano- 

 soma are similarly treated and prepared. 



c. Section preparations 



Paraffin sections should be made according to usual histological 

 technique. Fixatives and stains are the same as those mentioned for 

 smear preparations. 



References 



Balamuth, W.: (1951) Biological studies on Entamoeba histolytica. 

 III. J. Infect. Dis., 88:230. 

 • and Sandza, J. G.: (1944) Simple, standardized culture me- 

 dium for physiological studies on Entamoeba histolytica. Proc. 

 Soc. Exper. Biol. Med., 57:161. 



Bass, C. C. and Johns, F. M.: (1912) The cultivation of malarial 

 Plasmodia (Plasmodium vivax and P. falciparum) in vitro. J. 

 Exper. Med., 16:567. 



Becker, E. R.: (1926) Endamoeba citelli, etc. Biol. Bull., 50:444. 



Belar, K.: (1928) Untersuchungen der Protozoen. Methodik. wiss. 

 Biol., 1. 



Bijlmer, J.: (1948) On the recovery of Protozoa and eggs of some 

 species of helminths in human faeces. J. Parasitol., 34:101. 



Boeck, W. C. and Drbohlav, J.: (1925) The cultivation of Enda- 

 moeba histolytica. Am. J. Hyg., 5:371. 



Chatton, E. and Brodsky, A.: (1909) Les parasitisme d'une Chy- 

 tridin£e du genre Sphaerita, etc. Arch. Protist., 17:1. 



Claff, C. L.: (1940) A migration-dilution apparatus for the sterili- 

 zation of Protozoa. Physiol. Zool., 13:334. 



