1916] Wilson: On tlie Life-Hislori) of a Soil Amoeba 273 



flagellate stage lias not been found and limits iXaeyln-ia to tliose in 

 which a biflagellate stage occurs. This takes a number of species out 

 of the genus Vahlkampfia which will have to be put back in case all 

 placed in Vahlkampfia prove to have a biflagellate stage, and the 

 occurrence of a biflagellate stage will have to be made a generic 

 character of the genus Vahlkampfia. As a matter of convenience it 

 may be well, pending further investigation, to use the distinctions as 

 Calkins proposed them. 



Calkins gives the generic characters of Naeglrria a,s follows: 



Small limax-like forms with no essential morpholoiiical differences from 

 Vahlkampfia, except for the fact that the adult amoebae acquire and lose flagella 

 under conditions not fully recognized. They are viable, possess one contractile 

 vacuole and a single nucleus of the Umax type. The flagellated stage has a 

 definite oval form. Nuclear division promitotic; division of the flagellate stage 

 unknown in the majority of cases. 



The genus, then, to which the species described in this paper belongs 

 is Nacglcria Alexeieff. 



The species on which this work has been done resembles certain 

 other d&scribed species of Amoeba very clo.sely as far as the life-hi.story 

 has been worked out. The species A. gruberi described by Schardinger 

 (1899) agrees with it in all of the characteristics which he has given. 

 The habitat, however, is different. In this regard he says in one place 

 "Ich vermochte, ohne sonderliche Miihe aus Wasser eine Amoeba 

 spinosa, eine andere A. lobosa (ohlon^a) . . ." Later he says " Da die 

 Amijbe aus einem diarrhoischen Stuhle gezuehtet ist . . ." 



These are the only places where Schardinger mentions his .sources. 

 It is possible that he may have obtained a soil amoeba in his culture 

 of diarrheal forms, but what the possibilities of contamination were in 

 his cultures is not clear from his paper. On the other hand, however; 

 the cyst may have passed through the intestinal tract uninjured with 

 excystment taking place in the water from which the culture was made: 

 or, since amoebas live almost everywhere that bacteria are found, it is 

 possible that it may have endured or may have even become adapted 

 temporarily to the habitat of the digestive tract. 



Schardinger calls the species Amoeba lobosa evidently by way of 

 allocating it in the system of Rhizopoda, but not as a generic and 

 specific designation ; in other words, it is a limax form. The size in 

 locomotion is .32-4()ja long and 16-24/x wide, with an occasional larger 

 one. The pseudopodia are of ectoplasm only. There is one contractile 

 vacuole. The nucleus has peripheral chromatin slightly evident or 



