114 



RESEARCH IN PROTOZOOLOGY 



down the growth of many types of bacteria, but did not affect the 

 rate of multipHcation of the trichomonads. 



"Now that a method had been developed for growing the 

 trichomonads in great quantities and without the tremendous over- 

 growth of bacteria that usually occurs, the possibility of freeing 

 the organism of bacteria seemed more promising. Many physical 

 processes were employed, but most of them 

 met with little or no success and will not be 

 described here. In the earlier experiments 

 the organism was washed in sterile sodium 

 chloride in concentrations varying from 0.5 

 to I per cent. After the trichomonads had 

 been washed in saline three or four times, 

 they were suspended on the surface of sterile 

 saline in an upright tube ten feet long. The 

 organisms, being larger and heavier than 

 bacteria, would fall downward through the 

 saline faster than the bacteria, and it was 

 possible, in a few instances, to collect drops 

 of saline from the bottom of this tube which 

 contained from one to three trichomonads 

 each and no bacteria. Twenty drops were 

 taken in succession by opening the stopcock 

 at the end of the tube (the lower end of the 

 tube was well protected from contamination 

 of air microorganisms by a tube twice its 

 size fitting over it and extending beyond it. 

 The large tube was plugged with cotton. The 

 entire apparatus was sterilized in the auto- 

 clave). Ten of these drops (every other one) 

 were placed on glass slides and examined 

 microscopically for trichomonads, and ten 

 were placed in sterile serum-saline medium. 

 Some of these drops contained no trichomonads, while others con- 

 tained from one to three organisms each. About half the tubes 

 inoculated in this manner showed no bacterial growth after ten 

 days. Approximately two hundred tubes were inoculated in this 

 way, but Tritrichomonas did not grow in any of them unless bac- 

 teria were present. These results indicated that Tritrichomonas 

 was not able to grow without bacteria — at least not in any of the 



Fig. II.— Apparatus 

 for sterilizing and 

 tubing media. (After 

 Cleveland, 1928.) 



