Polymastigida 65 



into cotton-stoppered vials half full of sterile 0.75% saline solution. The 

 vials are taken to the laboratory, a drop of the fluid placed on a slide, 

 covered, and examined. Under low power ( 16 mm. objective) the para- 

 sites cannot be seen, but if they are present their movements cause violent 

 agitation of the corpuscles, thus enabling a tentative diagnosis to be made. 

 They are readily seen under high power (4 mm. objective) if the light 

 is carefully regulated. About 5 to 10% of the wild rats carry infections. 



To establish the strain in laboratory animals the fluid from positive 

 vials is drawn into a clean hypodermic syringe, and intraperitoneal inocu- 

 lations are made into partly grown laboratory rats, about 0.5 cc. being 

 given each one. Occasionally an animal will be found to be immune. 

 This fact necessitates the infection of several so as not to lose the infec- 

 tion. About seven days later a test is made. The tip of the tail is cut off 

 and a drop of blood allowed to mix with a small drop of saline solution 

 on a slide. It is then covered and examined microscopically. 



By the end of the second week the trypanosomes have usually reached 

 their maximum number and have begun to decrease. By the fourth or 

 fifth week (occasionally somewhat longer) they may have disappeared 

 entirely from the blood. Before this time it is necessary to inoculate 

 new, non-immune animals. An infected rat is etherized; the needle of a 

 hypodermic syringe partly filled with saline solution is inserted into the 

 heart; and some blood is drawn out. This is injected directly into the 

 peritoneal cavity of the new animals. By repeating the transfer of in- 

 fective serum at the proper times the strain may be maintained for in- 

 definite periods. 



Occasionally it is desired to keep living trypanosomes for a few days in 

 the serum-saline mixture. This may be accomplished by placing the 

 container in a refrigerator (about 18 C.) where they will live for a week 

 or longer. 



References 



For the culture of Oicomonas see p. 62. 

 Family Bodonidae 



For the culture of Embadomonas see p. 88. 



Order polymastigida 



NOTES ON CULTURING CERTAIN PROTOZOA AND 

 A SPIROCHAETE FOUND IN MAN 



M. J. Hogue, University of Pennsylvania Medical School 



MEDIA USED 



Locke-Egg medium. One hen's egg is thoroughly shaken with glass 

 beads in a flask. Add 200 cc. of Locke solution (sodium chloride 0.9 gm., 



