346 OHIO BIOLOGICAL SURVEY 



(d) ACKNOWLEDGMENTS. 



It is appropriate to note that much of the systematic work on 

 the Euglenoidina by the writer has been based on material obtained 

 in connection with investigations made possible through the Emer- 

 son McMillin Fund. 



2. Structure. 



The Euglenoidina are typically elongately oval or spindle- 

 shaped in form with a length of from 6-500 microns. They are 

 provided with a single (rarely two) flagellum (1) arising from a 

 cytopharynx (5) and consisting of an axial filament (2) sur- 

 rounded by protoplasm (3). They possess either a rapid rotatinqr 

 swimming movement drawing themselves forward by means of 

 the flagellum, or a creeping, twisting (metabolic) movement. 



The protoplast (22) secretes a periplast (21) which may be 

 thin or thick and covered with longitudinal or spiral striae (18) 

 composed of punctuations (19). The protoplast often secretes a 

 shell in addition to the periplast, which may be covered with spines 

 or other formations. The stigma (6) normally present in the 

 green Euglenidae varies from orange red to a dull yellow. There 

 is usually present a large vacuole (9) with a vacuolar canal open- 

 ing into the reservoir (7), narrowed anteriorly into a cytopharynx 

 (5), and one or more contractile vacuoles (8) which empty into 

 the large vacuole. 



In various genera chloroleucites (17, 23) give the protoplast 

 a green color and may be disciform, with the margin smooth or 

 deeply notched, ribbon-like, or aggregated into star-like clusters. 

 Paramylon (12, 20) in granules of various forms often con- 

 taining a distinct pyrenoid (24) may also be present as a product 

 of assimilation. The position of the nucleus (14, 15), particu- 

 larly in the green forms, is designated by a clear space near the 

 middle of the body and consists of a central (15) mass surrounded 

 by chromosomes (14). Near the nucleus and only demonstrable 

 by careful technical methods there is often a basal granule (bleph- 

 roplast?) (16), from which the flagellum may arise by two fila- 

 ments (10). In the family Peranemidae a pharyngeal siphon 

 (11) or rod-like organ of uncertain function is often present. 



