ISO 



HERl'ETOMONAS LVCi.i;i 



Acliiily of the 

 tiagellates 



I )evelopnient 

 Ant slagc 



I'littoii ill his paper described the life-cycle of this herpetonioiias as occurring in 

 tlueo difleri'iit stages whicii he names the preHagellate, flagellate and post-flagellate. 

 All these stages can be respectively seen in various parts of the alimentary tract of 

 f/i/ijHiiif militaris. 



If a hanging-drop preparation of tlie crop contents be examined, adult Hagellutes can be 

 observed, but not in very great numbers. They appear t" be more plentiful in the small 

 mid-intestine. 



They are actively motile and display various types of movement, the commonest 

 of wliich is a jerky, wriggling motion, with the flagella end forward, the latter vibrating 

 vigorously ; this movement is often followed by a peculiar gliding one in which the 

 flagellum is in a state of quiescence, standing out from the btxly in a straight line. 

 At other times the tiagellnni displays lashing movements, and occasionally the 

 herpetoinonad moves forward by means of its posterior end, while the flagellum trails 

 behind. When the latter becomes attached to any object the body appears to bend, 

 and sways to and fro in a rhythmical manner, at the same time twisting on itself. 

 Tlie twist nuiy occur both ways from right to left and vice versa. Sometimes the flagellate 

 appears to rotate on its own axis showing a peculiar action resembling the movements 

 of a " Catherine wheel." All these movements are brought about by the presence of 

 myonemes in the body of the flagellate. Waves of contraction pass along these body 

 myonemes from the posterior to the anterior end. These waves of contraction can be 

 well seen in the herpetoinonad just prior to its eucystment, when its movements become 

 very sluggish. 



As each wave ot contraction passes along the body, small refractile granules can ijc 

 seen alternately advancing and receding down the flagellum for about a third of its length. 



The Pkei'l.vgei.late Siwge 

 Plate XL, figs. 1-6 



If the crop contents be examined for the presence of cysts, very few will liu found ; 

 this is due to the fact that such a rapid development of the cyst occurs in the crop 

 that practically only flagellates are found. The early cystic stage is really best studied 

 in the fieces where they are more numerous. 



The preflagellate stage in Leishman-stained specimens are small, oval, pyriform 

 or round cells, 2-4^ x 1 - l-5;j, with a pale blue cytoplasm, limited by a sharply 

 defined edge or periplast. The pink trophonucleus is most often situated at the rounded 

 end of the cell, and is either circular or bean-shaped, measuring about l/i. When stained 

 bv iron hajmatoxylin, and suitably differentiated, a distinct nuclear membrane is apparent, 

 but at this stage of the parasite chromosomes are rarely seen. 



The kinetonucleus occupies a position anterior to the trophonucleus, and appears 

 as a dark staining rod or dot in the more pointed or anterior portion of the cell. Vacuoles 

 are occasionally to be found in the cell cytoplasm, and at this stage the flagellum may 

 appear arising from the vicinity of the kinetonnc1<Mis and reacbint,' the exterior as a 

 pink streak. 



The first stage in the further development of the parasite is a general enlargement 

 botli in length and breadth, and the cell cytoplasm appears very markedly reticulated. 

 The trophonucleus enlarges in size, and may occupy half, or more than half, of the cell area. 

 The parasite, instead of appearing as a short compact little cell, now resembles a delicate 

 structure more or less pear-shaped and measuring about (J^i in length. A clear area 

 now begins to form round the kinetonucleus, wliicli at this stage begins to elongate, 



