174 PROTOZOAL PARASITES 



the deeply staining rod-shaped " kinetonucleus " (blepharoplast of 

 many authors) (k.) lies, usually, in a transverse position. The 

 single stout flagellum, which is a little longer than the body of 

 the flagellate, arises from the anterior end, near the kinetonucleus. 

 Prowazek describes the flagellum as being of a double nature and 

 having a double origin ; this, which is a mistaken interpretation 

 is repeated by Lingard and Jennings (1906). Prowazek (1913) 

 has corrected what he considers misinterpretations of his original 

 statements concerning H. nniscae-domesticae. By statistical 

 methods he has found that the gi'eater number of the flagellates 

 examined in Rovigno are biflagellate. 



This mistake concerning the double nature of the flagellum 

 was pointed out by Leger and Patton, and their ideas have since 

 been confirmed by Porter, Mackinnon and Wenyon, who have 

 studied this and other species of Herpetomonas. In some flies 

 Porter found that practically every H. muscae-doniesticae which 

 was seen exhibited the so-called " double-flagellum." The appear- 

 ance of a double-flagellum represents the beginning of the longi- 

 tudinal division of the flagellate (VI). Patton (1908) figures a 

 stage in H. lygaei with a double-flagellum, and Leger (1902) and 

 Porter found the same appearance in H. jaculiim preparatory to 

 division. From the figures that these authors give it may be 

 understood how this mistake has arisen. Through this misinter- 

 pretation Prowazek was led to consider that the parasite was of a 

 bipolar type, in which the body has been doubled on itself so that 

 the two ends came together and the flagellum remained distinct. 

 The flagellum, according to Leger, is continued into the cytoplasm 

 as a thin thread, which stains with difliculty, and terminates in a 

 double granule above the kinetonucleus; this double granule is 

 no doubt the " diplosome " of Prowazek. According to the latter 

 author another deeply staining double thread {s.t.), that appears 

 to be spirally coiled, runs backwards from the kinetonucleus and 

 terminates posteriorly in a distinct granule, shown in fig. 77, VIII. 

 Wenyon (1913) believes that a cytopharynx is present, using as 

 an argument the presence of bipolar bodies which he believes are 

 bacteria taken up by the Herpetomonas. 



The flagellates congregate in the proventriculus or in the 

 posterior region of the intestine, where they become united by 



