1074 



PATHOGENIC PROTOZOA 



(protected with a cover glass and vaseline) it is actively motile, 

 but the undulating membrane is difficult to detect until the move- 

 ment has slowed down. 



The presence of cystic forms has been questioned, and two quite 

 different forms have been called resistance or dauer cysts. The 



earlier one, described by Ucke (1908), 

 Bohne and von Prowazek (1908), and 

 Benson (1910), is a fairly large body, 

 showing a double contour and a central 

 homogeneous mass, perhaps food material, 

 and an outer ring-like body containing 

 two or more nuclei. Brumpt and Alexieff 

 believe this form to be a fungus, having 

 no relation to the trichomonad, and have 

 called it ' ' Blast ocystis hominis. ' ' Lynch 1 

 agrees with these authors, and describes 

 an altogether different body as the re- 

 sistant form. It is six by eight microns 

 in size and perfectly symmetrical in 

 shape. The wall is distinct, and there 

 is a clear space between it and the body 

 of the parasite. The nucleus, undulating 



membrane and flagella remain visible in 

 FIG. 132\-TmcHOMONAS IN- the t but L h was unable to detect 

 TESTINALIS. (After Brumpt, . . 



"Precis de Parasitologie," an * v chan g e m the parasite indicating m- 

 1914 ed.) tracystic multiplication. 



Infection takes place probably by con- 

 tact, and, as in typhoid fever, food, fingers and flies carry the resistant 

 forms from one individual to another. Among the natives of tropical 

 countries infection is almost universal, but the parasites are rarely 

 seen in the large cities of the North. 



GENUS 2. Tetramitis mesnili (Wenyon, 1910). Macrostoma mes- 

 nili, Ckilomastix mesniU, Fanapapea intestinalis. This organism, first 

 described by Wenyon, from a native of the Bahamas, differs from 

 trichomonas by the possession of a deep groove or cystostome, in 

 which is found the undulating membrane. It is present in diarrheal 

 discharges, but its pathogenicity is doubtful. 



GENUS 3. Giardla intestinalis (synonym, Lamblia intestinalis). 

 The giardia are bilaterally symmetrical, pear-shaped organisms, 



1 Lynch, Kenneth M., Jour. Parasitol., Urbana, 1916, iii, 28. 



