HKIil'ETOMONAS ASl'ONGOPI 20;") 



of faces containing resting forms. No parasites were observed in conjugation, nor could 

 male or female forms be distinguished. 



Patton has drawn attention to the resemblance between Herpotomonas lygaei and 

 the Leishman-Donovan body, and this flagellate also offers a similar resemblance, 

 consequently it belongs to the same category. The flagellate stage is distinguished by 

 the formation of a typical flagelluni, and by division and multiplication of the flagellates. 

 The non-flagellate stages closely resemble the Leishman-Donovan body, the parasite in 

 the resting stage dividing into two parasites, which afterwards develop into two 

 flagellated forms. 



For some time past there have been consideral)le ditt'erences of opinion concerning 

 the ancestry of hiBmoflagellates. According to Minchin's view the htenioflagellates 

 were originally parasites of the intestines of vertebrates, whence they wandered into 

 the blood stream, and wei'e taken up later by bloodsucking insects, thus becoming 

 parasites of a vertebrate and of an invertebrate host. This hypothesis applies to many 

 forms of hsemotlagellates, but, as Prowazek pointed out, HerpetmitoiKa: ini(i'c;e donimticce 

 is a true parasite of the house-fly ; this insect is not a blood-sucker although its ancestors 

 may have been, as a study of the mouth parts of the house-fly appears to indicate. 

 Herpetomonas aspongopi is likewise a true parasite of Asponrjopus viduatim, which is not 

 a blood-sucker. Many of the Hemiptera are fierce blood-suckers, as, for example, the 

 bed-bugs {Acanthia). The beak-like mouth parts of the bed-bugs bear a definite 

 resemblance to the month parts of the plant-feeding bugs, therefore it might be claimed 

 that the ancestors of tlie latter were originally blood-suckers, and that they had originally 

 become infected with Herpetomonad forms from some vertebrate host. 



I should like to thank Dr. Balfour and Captain Archiliald, R.A.M.O., for theii' kind 

 help and advice. 



