70 RESEARCH IN PROTOZOOLOGY 



is the medium of choice for the growth. In the hands of the writer, 

 the serum-sah solution medium, especiaUy with the modification 

 of Hegner, has proven the simplest in preparation and has given 

 the most profuse growth of any of the others tried. In addition, 

 the precipitates formed by bacterial growth have apparently been 

 less in quantity, and less harmful to the growth of protozoa. 



CULTIVATION OF SPECIFIC ORGANISMS 



The cultivation of the intestinal amoebae is taken up in another 

 chapter of this book. The remaining protozoa infesting the human 

 intestine may be classified for our purposes, as, (a) those passing 

 their entire life cycle in the intestine, and (b) those requiring an 

 intermediate host for their complete development. Obviously, cul- 

 tural methods can be applied only to the former class. 



The known human intestinal protozoa belonging to (a) are: 

 (i) Trichomonas hominis, (2) Embadomonas intestinalis, (3) 

 Giardia lamhlia, (4) Enteromonas Jwminis, (5) Chilomastix mes- 

 nili, and (6) Balantidmm coli. 



Of these organisms, Giardia and Enteromonas have not been 

 cultivated. 



Trichomonas hominis was first cultivated by Lynch (191 5) on a 

 medium composed of acidified bouillon. His cultures multiplied at 

 first, but lived only a few days. Boyd (1918) attempted the culti- 

 vation of this organism in sterile salt solution to which was added 

 non-sterile fecal material. This is apparently an example of pre- 

 serving the life of the organism, rather than cultivating it. The 

 writer has preserved living Trichomonas for months in various 

 media, keeping the cultures in an ice-box. In the hands of the 

 writer, the most favorable medium for the cultivation of Tri- 

 chomonas is serum-salt solution, as used by Barret and Smith 

 (1924). Cysts of Trichomonas are unknown. 



Embadomonas intestinalis. ''Hogue (1921) was the first to cul- 

 tivate this species using the ovomucoid medium described above 

 and also a Locke-egg medium and an ox bile salt medium. Cysts 

 appeared in tubes that contained no other protozoon ; this is appar- 

 ently the first authentic record of the formation of cysts by any 

 intestinal flagellate in cultures." — Hegner and TaHaferro (1924). 



Chilomastix mesnili was first cultivated by Boeck (1921) using 

 a medium composed of human serum and Locke's solution with 

 the addition of a small amount of dextrose. 



