TKICHOMONAS VAGINALIS 825 



Chalachnikow distinguishes two varieties of trypanosomes in fish ; one similar 

 to T. avium, the other, flat and not folded, like T. rotatorium. Numerous species 

 are now described : T. remaki, T. danilewskyi, T. dbramis, T. rajce, T. solece, etc. 



FIG. 398. Fish trypanosomes. (After Chalachnikow.) 



For the detection of the parasites in the blood, Laveran and Mesnil advise col- 

 lecting a few drops of blood by incising two or three rays at the base of the dorsal 

 fin. The blood should be examined between a slide and a cover-glass. Mixing the 

 blood with a little citrated normal saline solution prevents coagulation and preserves 

 the motility of the parasites. 



For preparing stained preparations the living fish must be opened and some of 

 the heart blood collected in a pipette : the blood is then to be spread on slides in a 

 thin layer, rapidly dried over the flame of a spirit lamp and then fixed in absolute 

 alcohol or in alcohol-ether. 



SECTION II. TRICHOMONAS VAGINALIS. 



Syn. Cercomonas intestinalis. Trichomonas intestinalis. 



It is now generally conceded that the parasites described under the names 

 of Cercomonas hominis (Davaine), Cercomonas intestinalis (Lambl), Tricho- 

 monas intestinalis (Leuckart), etc., should be regarded as a single species : 

 Trichomonas vaginalis (Donne, Blanchard). 



Trichomonas vaginalis was discovered by Davaine in the dejecta of persons suffering 

 from cholera. It is frequently to be found in the stools of patients suffering from 

 diarrhoea due to very different diseases. It has been found in the viscous fluid sur- 

 rounding an hydatid cyst of the liver (Lambl), in cases of gangrene of the lung, 

 hydropneumothorax, etc. It is frequently present in the vagina in cases of vaginitis 

 in married women and virgins, but not in normal alkaline vaginal mucus. It has 

 been found in the bladder. 



In some cases of dysentery Trichomonas is found in very large numbers (Castellani, 

 Terry, Chassin, Billet) and may be found in association with Amoeba histolytica. 

 The part it plays in disease processes is not clear : there is no proof that alone it can 

 give rise to dysenteriform ulceration. It is conceivable that it may find a suitable 

 soil for development in, and may perpetuate, some pre-existing lesion. 



According to Perron9ito, the parasite gains entrance to the alimentary canal in 

 drinking water, in which it occurs in an encysted form. 



Morphology. Trichomonas vaginalis measures 12-25//, long by 7-1 2/* 

 broad. Its shape is very variable ; it is generally pyriform, though some- 

 times pointed, sometimes curled up into a rounded ball, and sometimes 

 constricted in the centre like an hour-glass. The larger anterior end is 

 furnished with three sessile flagella directed forwards all attached at the 

 same point and frequently matted together : there is a fourth flagellum turned 

 backwards forming the free margin of a slightly raised, folded and scalloped 

 undulatory membrane which extends to the posterior end of the organism. 

 The posterior end is most frequently provided with a caudal appendage of 



