PLATE 5 



Figs. 73-92. Nectomonads from pyloric expansion (Figs. 73-80). A series 

 of elongate, slender flagellates from crithidial infection of the pyloric expan- 

 sion. Vesicular types of nuclear structure in figures 73, 75, 80. Chromatin 

 broken up into granules in figures 74, 76, and 79. Chromatin of nucleus on 

 the membrane in figures 77, 78. 



Figs. 81-86. Another group of nectomonads from pyloric expansion, illus- 

 trating the changes "which take place in shape of body, length decreases, width 

 increases. These are shorter, broad types of crithidias, and probably come 

 from the longer, more slender forms. Nuclear structure usually shows the 

 central karyosome. Figure 82 shows the chromatin broken up, a condition which 

 may indicate an early stage of degeneration of the nectomonads. 



Figs. 87-90. Transition flagellates from nectomonads to haptomonads. By 

 a process of binary fission these transition forms become reduced in size. Cer- 

 tain nectomonads become attached to wall of the pyloric expansion or they 

 form haptomonads. Others degenerate before reaching this stage. 



Figs. 91-92. Free flagellates. Their size is doubtless due to a process of 

 binary fission and they resemble the attached haptomonads of the pyloric 

 expansion. They are either nectomonads which are about to become hapto- 

 monads or vice versa. If the latter, the haptomonads upon becoming free again 

 usually degenerate at once. 



[188] 



