356 



APPENDIX. 



or absent By very careful focusing on the upper edge of 

 the central portion, the author discovered the existence, 

 much more markedly in some of the parasites than in 

 others, of a longitudinal membrane with either a straight 

 or undulating margin (Fig. 132). The membrane is 

 attached along the body, arising from the base of the 

 rigid filament, and becomes directly continuous at the 

 opposite end with the flagellum. In some cases the edge 

 only is deeply stained, giving the appearance of a thread 

 continuous with tJie flagcllum^ so that one might be easily 

 led to overlook the membrane, and imagine that the 



FIG. 132. "SURRA" PARASITES OCCURRING SINGLY AND FUSED. 

 From preparations stained with magenta, X 1200. 



flagellum arose from the opposite end of the body, at the 

 base of the spine-like process. 



Close to the base of the spine-like process a clear 

 unstained spot is, in many parasites, easily distinguished, 

 and at the opposite end there is, in some, the appearance 

 of the deeply-stained protoplasmic contents having con- 

 tracted within the faintly-stained cell-wall. Where the 

 longitudinal membrane has a wavy outline the undulations 

 are much more marked in some cases than in others. 

 Here and there the wavy outline appears first on one side 

 of the central portion, and then on the other, but there 

 never is any waving outline on both sides of the same 

 part of the body, and this is explained by careful exami- 



