1917] McCulloch: Crithidia euryopht.Jta.lmi 85 



preparations can be used as a definite evidence, this process does not 

 play an important part in increasing the numbers of flagellates. The 

 small number of preparations of the crops which show an infection 

 leads to the conclusion that the developing flagellated forms and zooids 

 pass back into the mid-stomach and into the pyloric expansion after 

 a very short period of development in the crop. 



Forms from the Mid-Stomach 



The series of forms found in the mid-stomach are shown in figures 

 13-19. These may be divided into three classes: (1) the small oval 

 spore forms (fig. 19) and small zooids, (2) nectomonad or free flagel- 

 lated forms (figs. 1, 4—18), and (3) haptomonads or attached forms 

 (fig. 13). Owing to the relatively'' small percentage of infection of 

 the preparations in the mid-stomach as • compared with that of the 

 preparations from the pyloric expansion, there is probably a migra- 

 tion of the parasites from this portion of the mid-gut into the pyloric 

 expansion. 



The oval spore forms and zooids occur very frequently in the 

 preparations from the mid-stomach. The question as to whether they 

 normally develop into flagellates in tliis region can not be answered 

 as yet. The serial sections of the region show these non-flagellated 

 forms in the lumen when few or no nectomonads can be detected. 



The nectomonads of the mid-stomach do not show any signs of 

 degeneration, the nucleus has the characteristic chromatin, encrusted 

 nuclear membrane and central karysome (fig. 17). The cytoplasm 

 also is normal in appearance. The study of these forms indicates that 

 the first signs of degeneration of C. euryopMlialml are to be found 

 in the cytoplasm. The external surface of the body is likewise free 

 from adherent bacteria. 



The haptomonads (fig. 13) are attached to the epithelial cells in 

 the posterior portion of the mid-stomach. The haptomonads, or 

 attached forms are elongate, slender flagellates which resemble the 

 free nectomonad forms. The serial sections of this region show 

 epithelial cells lining the lumen to be intact. The cell walls are 

 clearly outlined with the fringe of parasites on the outside. The 

 cj'toplasm of these epithelial cells is vacuolated but other than this 

 there is little indication of any degeneration of this epithelial lining. 



Forms from the Pyloric Expansion 

 In the p3'loric expansion of the stomach proper the same forms 

 just described in the mid-stomach are to be found, namely: the oval 



