Amoeba ferox, discovered in riverwater

Abstract

In the course of our investigation on the presence of bacteriophage in water tak en from a river at Malan g, Java we discovered a new Amoeba. It is small-5-28 average about 15 μ in diameter-very actively motile and possing a well developed ectoplasm and a entoplasm with a h a nuclea and one or some vacuoles. It can be easily cultivated on ordinary ag ar and in broth inoculated with Bacillus typhosus or other bacteria a nd on the agar makes a “plage” “bare spot”, which, different from the “pla qe” due to bacteriopha.ge activity of d'Herelle, shows not only a marked in, crease in size as soon as the plage is formed, but does continues to g row until the whole plate is clear, all the bacteri a having been eaten. The plage starts from one point and grows bigger and bigger, and at its ed ge we can see the amebes arranged in rows and some amebes moving out, wards penetrating slowly into the bacterial g rowth.
This mybe a new Amoeba and we propose s.very activ eAmoeber “Amoeba ferox” because of the great voracity in eat, ing-up different strains of pathogenic bacteria, Bacillus ratyph A, Paratyph B, Bac. dysenteriae (Shiga, Flexner, Sonne.) and also B. coli.