STUDIES ON AVIAN H^M0PROTOZOA. 685 



daughter-individual elongates a little and becomes spindle- 

 shaped instead of pyrifonn ; the membrane also becomes 

 more conspicuous. I have not seen any transitional phases 

 between these fusiform individuals and the type represented 

 by the parent form, and have therefore no indications as to 

 whether they (the former) grow or otherwise pass into the 

 accentuated trypanomonad type again. By successive multi- 

 plication according to this manner the size of the parasites 

 become considerably reduced. In fig. 102 is seen a vei*y 

 small couple of the kind described. Examples of free 

 parasites, of different sizes, representing accentuated trypano- 

 monad daughter-individuals are given in figs. 105 and 

 108-110, 108 being from a redpoll culture, the others from 

 a chaffinch one. The smallest form (fig. 110) is lOh ju long, 

 its flagellum is IS fi, and its breadth is 2^ ju. The small fusi- 

 form parasite of fig. Ill, representing a pyriform daughter- 

 individual, is 9 fx long, its flagellum is 7^ ju, and its width 2^ ^. 

 The great majority of the pai-asites in thriving cultures 

 belong to the above-described types. After a fresh culture- 

 tube has been inoculated (from a bird) about five days, 

 by which time the trypanosomes have generally multiplied 

 sufficiently to ensure that there will be a fair number of 

 parasites on a permanent smear — in other words, that an 

 individual can be found without much searching — practically 

 all the parasites present conform to the trypanomonad type. 

 And up to the end of a week or so this type persists with 

 great constancy^, notwithstanding the rapid multiplication. 

 The only variations that are numerically important are those 

 already indicated, in the direction, that is, of an accentuated 

 trypanomonad type and of a fusiform one. Further, if a 

 sub-culture of these normal forms is made (preferably not 

 later than the seventh or eighth day) the development of 

 similar forms continues steadily in the sub-culture. Thus 

 the parasites drawn in figs. 74, 109, are on a preparation 

 from a second sub-culture, and the total interval that had 

 elapsed since the blood was originally taken from the bird 

 was twenty-six days, or over three weeks. 



