THE EUGLENOIDINA OF OHIO 353 



or consist of an annular thickening, etc. ; structure of periplast— 

 elastic or metabolic, firm, striated either spirally or more rarely 

 longitudinally, the striae consisting of minute elevations as a rule, 

 development of a shell with or without spines, punctuations, wart- 

 like processes, etc. ; chloroleiicites (chloroplasts) absent or present 

 in the form of ribbon-like bands, elongated cylindrical rods, disks 

 with margins smooth or lobed, star-like masses, all of which may 

 or may not contain pyrenoids; paramylon with granules of vary- 

 ing forms, usually elongately spherical ; pharyngeal siphon, a rod- 

 like organ of unknown function present in certain Peraneynidae; 

 stalk present in a few forms, long, short, branched or not 

 branched ; length of flagellum as well as the number and position 

 where two flagella are present ; stigma present or absent, etc. The 

 structural position of the characters noted is indicated in Fig. 1 

 on a preceding page. 



Many other minor characters are used, mention of which will 

 be made in the tables for separating genera and species. 



(c) METHOD OF STUDY. 



Material from standing water — small ponds, stagnant pools, 

 ditches, etc. — particularly where organic matter is in a state of 

 decomposition, will invariably yield many interesting species of 

 the Euglenoidina. If such material is placed in small bottles where, 

 however, it should not remain more than 48 hours with the stoppers 

 inserted, and then only when an air space approximately equal to 

 one-third the capacity of the bottle is left, and subsequently trans- 

 ferred to aquaria, the scum rising on the surface within the course 

 of a few days will contain innumerable forms. Ordinary drinking 

 glasses make excellent aquaria. They should be provided with a 

 rectangular glass cover to prevent too rapid evaporation, although 

 this should not entirely close the top, thereby allowing the gases 

 arising in the decaying matter to escape. 



Many species of Euglenoidina occur as "plankton" carried 

 from place to place in large bodies of water by winds and currents 

 and may be obtained with a plankton net made of finely meshed 

 "bolting cloth" drawn through the water. 



If one wishes to ascertain the number of organisms present 

 in a definite body of water such as a reservoir or pond from which 



