HERPETOMONAS MUSC^-DOMESTICm 



365 



As already stated, there is considerable difference of opinion concerning the 

 status of the Herpetomoninae at the present moment. A number of observers, 

 including Leger and Sambon, look upon them as merely stages in the life-history 

 of trypanosomes ; while others, such as Novy, McNeal, Ross, and Patton, hold 

 that they are probably distinct from the blood trypanosomes . Woodcock, how- 

 ever, is correct when he says that those with trypaniform characters will 

 probably be found to be stages in the life-cycle of trypanosomes, while the 

 more typical herpetomonads will be found to be separate and distinct from 

 these parasites. 



In other words, some of the forms found in blood-sucking flies, leeches, etc., 

 may be stages in the life-cycle of trypanosomes, while other forms, together, 

 with those found in non-blood-sucking flies, and perhaps those found in larvae, 

 may (though it is open to question in the larvae of blood-suckers) belong to a 

 truly separate genus. The life-history of these forms has been mainly studied 

 by Prowazek and Patton, whose results differ remarkably. 



Herpetomonas muscae-domestiese Burnett, 1851. 



Synonyms. — Bodo musccs-domesticcB Burnett, 1851; Cercomonas musccB- 

 domesticcB Burnett, 1851 ; Leptomonas musccs-domesticcB Burnett, 1851. 



This flagellate is found in Musca domestica L., Homalomyia scalaris 

 Fa bricius, Po/^ewm rudis F., Theicomyza fusca Macquart, Lucilia sp. ?, Pycno- 

 soma pulorum, Scatophaga lutaria 

 F., Neuroctena anilis Fallen, and 

 Homalomyia corvina Verrall. 



Miss Mackinnon has given a 

 careful account of the morpho- 

 logy andT life-history of Herpeto- 

 monas musccB-domesticcB which 

 is found in the house-fly Musca 

 domestica Linnaeus. 



Morphology. — The preflagel- 

 late stage takes place in the mid- 

 gut, or more rarely the hind-gut, 

 of the fly in the form of small 

 round or oval bodies, 3 to 4 by 

 2*5 [ji, which possessacircular tro- 

 phonucleusandarod-shaped kine- 

 tonucleus, while a rose-pink area 

 in specimens stained by Giemsa, 

 running from the kinetonucleus 

 to the end of the cell, indicates 

 the position of the future flagel- 

 lum. This stage passes into the 

 flagellate stage which takes place 

 in the mid-gut when theHerpeto- 

 monad appears as a rather elon- 

 gated (25 ^ by 2*5 ij) body, which 

 is blunt at the afiagellar end, 

 and furnished with a flagellum 

 which measures 30 and arises 

 from a blepharoplast situate near 

 the kinetonucleus. The rhizo- 

 plast measures 4 ^, and is mark- 

 edly thickened. The rod-shaped kinetonucleus is situate 6 ^ from the flagellar 

 extremity, and measures 2 by o-8 ^. The trophonucleus is situate almost 

 centrally, and measures 3 ^ by 2 ^. The Doppelfaden of Prowazek is present 

 as a line from the kinetonucleus via the trophonucleus far into the aflagellar 

 end of the body. 



Life-History. — Herpetomonas musccs-domesticcs multiplies by longitudinal 

 division, in which the rhizoplast divides first, and each half is seen to have a 



Fig. 83. — The Life-Cycle of Herpeto- 

 monas musccs-domesticcB Burnett. 

 (After Patton.) 



I, Fully developed parasite; 2-5, stages 

 of encystment ; 6, encysted or preflagellate 

 form; ya-Sa, multiplication of the pre- 

 flagellate form by simple division; jb-Sb, 

 multiple division; 9, young flagellate 

 stage; 10, other form; 11, longitudinal 

 division commencing. 



