294 
ZOOLOGY: M. BUNTING 
Proc. N. a. S. 
A PRELIMINARY NOTE ON TETRAMITUS, A STAGE IN THE 
LIFE CYCLE OF A COPROZOIC AMOEBA 
By Martha Bunting 
Department of Zoology, University ok Pennsylvania 
Communicated July 24, 1922 
In 1920 a study of the Entamoeba of the rat was begun and in a culture 
on artificial medium a number of Coprozoic amoeba appeared, one of which 
exhibited a flagellate phase which seems to be identical with Tetramitus 
rostratus Perty.^ 
The appearance of flagellate phases in cultures of Coprozoic amoeba 
(Whitmore,^ etc.) as well as of soil amoeba (Kofoid,^ Wilson,'^ etc.) has 
been recorded a number of times, but the flagellates which appeared were 
relatively simple in organization and very transitory in occurrence. Fur- 
thermore, some of the simpler flagellates have been observed (Pascher^) to 
lose their flagella and become amoeboid. In the case here described, 
however, there is a transformation of a simple amoeba into a relatively 
complex flagellate which multiplies for several days then returns to the 
amoeboid condition and becomes encysted. Tetramitus rostratus has 
been studied by a number of investigators since its discovery in 1852, by 
Perty,^ yet no one has given a full account of its life history. The lack 
of cysts in previous accounts, mentioned by Dobell and O'Connor,^ is 
explained by the transformation into an amoeba before encystment. It is 
believed that this animal presents the extreme in transformations of this 
sort and serves to emphasize the close relationship between amoebae and 
flagellates, and the need for careful studies of life cycles, in pure cultures 
where possible, in investigations of coprozoic and other Protozoa. It is 
proposed to record at this time a brief account of the life history of this 
amoebo -flagellate reserving the more extended discussion for future 
publication. 
The amoeba in question was first observed on November 5, 1920 in 
coecal, material which had been taken from the rat and placed in sterile 
physiological salt solution on October 28, 1920. This is known as culture 
10. After discovery of the amoeba, transplants were immediately made in 
various media. The amoebae were subcultured several times on solid 
media over a period of about two months, then two cultures were made in 
fluid media. In one the formula given by Sellards,"^ namely, 1.0 gr. Witte's 
peptone, 0.5 gr. lactose, 1000 cc. distilled water was used; in another, 
dextrose was substituted for lactose in Sellards' formula. The medium 
containing dextrose proved to be much more favorable for the amoeba 
under consideration. In these liquid media a flagellate appeared which is 
thought to be Tetramitus rostratus Perty. 
