THE EUGLENOIDINA OF OHIO 355 



thus not crush the organisms as the water evaporates. A perma- 

 nent aquarium may be made by cutting the outside margin of the 

 lens-paper 2-5mm smaller than the cover glass and after the water 

 in this external area has partly evaporated (15-30 minutes) run- 

 ning a small quantity of paraffin oil around the margin of the cover 

 glass. Such an aquarium will retain organisms for a month or 

 more in a living condition provided there is a proper balance of 

 animal and plant life. 



By means of the lens-paper aquarium described the forms 

 may be studied with the 4mm. or even the 2mm. oil immersion 

 objective. If the movements are too rapid, they may be placed 

 in a 2-3 9f solution of gelatin, which will retard their activities. 

 Inverting a drop of water on a slide over the neck of a bottle con- 

 taining a 2% solution of osmic acid will instantly kill the forms, 

 usually without any distortion. Their life-like appearance may be 

 lost, however, and it is always best to study first under natural 

 conditions. 



(d) CHARACTERS OF THE ORDER EUGLENOIDINA. 



Order EUGLENOIDINA Blochmann. 



Euelenoidina Blochmann; Die mikoskopische Tierwelt d. Susswassers, 

 1895; Doflein, Lehrbuch der Protozoenkunde 1911, p. 505. 



Euglenineae Senn, Engler u. Prantl, Natiirliche Pflanzenfamilien, p. 173 I 

 Teil, Ab. la^. li> 1900. 



Euglenida Delage et Herouard, Traite de Zoologie Concrete, Tome 1, 

 p. 345. 



Eugleninae Lemmermann, Die Siisswasserflora Deutschlands, Osterreichs 

 und der Schweiz Heft 2, p. 115, 1914. 



Form elongately oval with a pharynx from which one or more, 

 rarely two, flagella extend ; body metabolic but not amoeboid, pro- 

 vided with a firm periplast which is often striated or sculptured ; 

 excretory system complicated usually with a comparatively large 

 reservoir into which one or more contractile vacuoles open ; ante- 

 riorly near the base of the pharynx a stigma ; protoplasm contain- 

 ing granules of paramylon while chromatophores may or may not 

 be present; nucleus large with central "Binnenkorper" ; reproduc- 

 tion agamous with a single or with multiple division, although 

 isogamous copulation has been observed in the genus Copromonas 

 (Scytomonas). 



