262 FAMILY: DIMASTIGAMCEBIDiE 



genus Dimastigamceba founded by Bloclimann (1894), its correct name 

 being Dimastigamceba gruberi. According to Boeck and Stiles (1923), 

 the name Dimastigamceba of Blochmann (1894, 1895) refers to another 

 amoeba, as also Alexeieff's name Ncegleria. They adopt the name Wasie- 

 lewskia, proposed by Hartmann and Schiissler (1913), and employed by 

 Zulueta (1917), for the form described here, which they refer to as Wasie- 

 leivskia gruberi. As, however, there is little doubt that the organism 

 described by Whitmore (19116) as Trimastigamoeba philippinensis is the 

 same amceba, his generic name has priority over all names except Dima- 

 stigamceba, which nevertheless appears to be the correct name for the 

 genus. 



It is evident that Dimastigamoeha gruheri might be classed with the 

 Mastigophora, instead of with the Rhizopoda. It illustrates very clearly 

 the close relationship of the two groups, 



Dimastigamceba gruberi (Schardinger, 1899). — This amoeba, which 

 occurs commonly as a coprozoic organism in faeces of human beings and 

 animals, has been studied by the writer in cultures made from dirty water 

 and old faeces. Both on agar plates and in liquid media the organism 

 remains in its amoeboid phase, but if sudden changes are made the 

 flagellate phase appears in two to three hours, and lasts up to twenty-four 

 hours or longer than this under exceptional circumstances. Thus, if some 

 of the growth on agar plates is scraped off and mixed with two or three 

 drops of tap water, in two or three hours, according to the temperature, 

 enormous numbers of flagellates are developed. In twenty-four hours 

 they have all reverted to the amoeboid form again. A further addition of 

 tap water brings about the reappearance of the flagellate forms. It is 

 quite easy to watch under the microscope the transformation of one of the 

 amoebae into the flagellate. The amoeba becomes rounded, and two 

 flagella commence to grow from the surface of the body. They can be 

 seen to be connected with two small granules, the blepharoplasts, which 

 lie close together on the surface of the body. The nucleus, which is 

 readily seen on account of its large retractile karyosome, may remain near 

 this point, or it may be at some other part of the amoeba, or its position 

 may be constantly changing. It has not been possible to observe the 

 origin of the blepharoplasts from the nucleus or its karyosome. They are 

 first detected as such after the flagella have commenced to form. The 

 flagella gradually increase in length, and become more violent in their 

 action. The organism now elongates and becomes pear-shaped, the more 

 pointed end being the flagellar end. The nucleus, if it has not remained 

 near the blepharoplasts during the growth of the flagella, approaches 

 this end of the body. At this stage the typical flagellate is formed. The 

 posterior region of the body is swollen, the anterior being narrow. At one 



