1923] Hall: Biliary Fission of Menoidixim incurvum 449 



MATERIAL AND TECHNIQUE 



Abundant material was obtained from an aquarium at Emory 

 University, Atlanta, Georgia. The flagellates became dominant early 

 in March, 1921, and were still plentiful in July. The aquarium in 

 which the form occurred measured about 36 by 18 by 24 inches, and 

 was filled to a depth of five or six inches with a mixture of mud, 

 sand, sawdust, old leaves, and straw. A small turtle and several 

 large tadpoles had been placed in the aquarium several weeks before 

 the appearance of the flagellates, and were kept there continuously. 

 Menoidium appeared to be uniformly distributed throughout the 

 aquarium, there being no marked accumulation at the surface. 



Several new cultures have been started at the University of Cali- 

 fornia from samples of the original material sent me from Emory 

 University. Menoidium has been present in these cultures fairly 

 constantly for the past year and a half, although never in such 

 abundance as in the first aquarium. Various attempts have been 

 made to obtain pure cultures in peptone and beef extract solutions, 

 boiled hay infusions, and different combinations of these, but none 

 was markedly successful. Some of the Protozoa which have occurred 

 in the cultures in association with Menoidium are: Euglena, Petalo- 

 monas. Cryptoglena, Amoeba, Difflugia, Arcella, ChiJomonas, Coleps, 

 Stylonychi-a, Euplotes, Loxophyllum, Centropyxis, Cydidium, and 

 Colpidium. In addition several species of small Crustacea, rotifers, 

 diatoms, and green algae have usually been present. 



In fixation, both the cover-gla.ss flotation and the centrifuge 

 methods have been used to accumulate material in quantity; the best 

 results have been obtained by centrifuging. As fixing agents, strong 

 and weak solutions of Plemming's fluid, and Schaudinn's fluid (both 

 hot and cold solutions) have been used; Schaudinn's sublimate-alcohol 

 has been more satisfactory. All staining has been done by the cover- 

 glass method. In the flotation method as well as with centrifuged 

 material, the cover-slips were smeared with a thin fllm of Mayer's 

 egg albumen fixative ; in the case of material killed after centrifuging, 

 the organisms were pipetted onto the smeared covers and then stained 

 in the usual way. Among the stains tried in addition to alcoholic 

 and aqueous iron-alum liaematoxylins are: Delafield's haematoxylin, 

 the mixtures of Mallory and Mann, Benda's safranin light-green, 



