378 University of California Publications in Zoology ["^'ol. 20 



may be associated in the stools. It appears from these records of 

 occurrence that Pentatrichomonas may have a wide distribution in 

 the tropics. 



It is important that the occurrence of epidemics of triehomonad 

 diarrhoeas reported from Colombia by Alvarez (1916), from Argen- 

 tina by Vaccarezza (1917), and from Arequipa by Escomel (1919), 

 be critically examined with reference to the presence of Penta- 

 trichomonas. 



MORPHOLOGY 



Pentatrichomonas ardin delteili has the typical organelles of the 

 triehomonad flagellates, namely, (1) the neuromotor system consist- 

 ing of the anterior flagella, undulating membrane, axostyle, blepharo- 

 plasts, eentrosome, and rhizoplasts, and (2) the other non-fibrillar 

 organs, the nucleus, and the cytostome. These differ structurally, if 

 at all, onlj' in minor details of proportions from those of other species 

 of trichomonads. 



The distinguishing characteristic of the genus is the presence of 

 five anterior tlagella. The genus Trichomonas Donne (1837) has 

 four and Tritrichomonas Kofoid (1921) has three. 



These flagella are slender threads of uniform and equal caliber 

 whose length exceeds slightly that of the body in normal extension. 



These anterior flagella fall into two groups as to origin and 

 behavior, a fact not hitherto noted and ignorance of which tends to 

 obscure the number of flagella. These maj' be designated respectively 

 as the single independent (ind. ant. flag.) and the three clustered 

 anterior flagella {chest, ant. flag., fig. A). 



The two groups arise from different blepharoplasts. The indepen- 

 dent flagellum arises, together with the undulating membrane, the 

 parabasal body, and possibly the axostyle also, from the proximal 

 or primarj' blepharoplast {prim, bleph., fig. A), while the three 

 chistered anterior flagella arise from the more distal or secondary 

 blepharoplast {sec.hleph., fig. A). 



Dobell and O'Connor (1921) state that there are at least three 

 and possibly more blepharoplasts and that the flagella appear to take 

 their origin from at least two of these; but they do not distinguish 

 the two groups of flagella nor state their relations to the blepharo- 

 plasts, nor that of the other organelles to these structures. Their 

 figures (their pi. 5, fig. 71) might be interpreted as showing two 



