General Morphology of the Protozoa 15 



capitulum (Fig. 1. 8, A, E). Many multinucleate species contain a num- 

 ber of axostyles, one for each mastigont, and the distal portions of the 

 axostyles form a bundle extending posteriorly as in Snyderella (Fig. 1. 

 8, C). 



Staining reactions of the axostyle vary in different species. Iron-hema- 

 toxylin stains the axostyle of Monocercomonoides pilleata (Fig. 1. 8, B) 

 but not that of certain other flagellates. The organelle appears homo- 

 geneous in some species, shows a sheath and a core in others (Fig. 1. 8, 

 A), and sometimes contains stainable granules (Fig. 1. 8, D). The axo- 

 style of Trichomonas termopsidis (124) is stained brown in iodine solu- 

 tion. 



Costa, cresta, pelta, and aciculum 



The costa (Fig. 1. 7, G; 1. 8, D) arises from a blepharoplast and 

 extends along the base of the undulating membrane in various tricho- 



Fig. 1. 9. AC. Pelta, different views, Hexamastix citelli; x6500 (after 

 Kirby and Honigberg). D. Aciculum of Cryptobia helicis; kinetoplast indi- 

 cated diagramraatically; x5330 (after Kozloff). E. Cresta, small type, Cadu- 

 ceia kofoidi; x3060 (after Kirby). F. Large cresta, Macrotrichornonas emer- 

 soni; shelf-like unguis attached; trailing flagelluni ribbon-like; xl425 (after 

 Kirby). Key: a, axostyle; ac, aciculum; cr, cresta; ct, cortex; k, kinetoplast; 

 71, nucleus; p, pelta; t, trailing flagellum; u, unguis. 



