lf>-'-i] Kessel: Anwihac of Culture Rats and Mice 497 



muris and Council mania decumani, the pseudopodia and the amoeboid 

 movement of the two species will be discussed together. 



Grassi (1881) in describing the amoebae of the rat and mouse said 

 that they are slightly motile and that two or more large and blunt 

 pseudopodia can be demonstrated. Ordinarily, only one is evident 

 at a single instant and this is retracted before the second is formed. 

 He described the pseudopodia as "hyaline," i.e., ectoplasmic, and 

 stated that the endopla.sm flowed into the ectoplasm, which he inter- 

 preted as the method by which the amoeba moves. 



Movement, according to Wenyon (1907), may be rapid on a warm 

 stage. He wrote, "As a rule only a single pseudopodium is formed at 

 one time. This consists at first only of ectopla.sm [his pi. 10, fig. 3] 

 into which the endoplasm suddenly streams, carrying the nucleus 

 with it." Brug (1919) stated that the amoebae creep about more 

 actively than he ever saw Endamoeba coli creep and that in the pseu- 

 dopodia only ectoplasm is found. 



Rudovsky (1921) found that the protruding pseudopodia are 

 plainly divisible into a transparent and a finely graniilar zone and he 

 differentiates between ectoplasm and endoplasm (his pi. 7, fig. 1). It 

 is evident from these descriptions that the amoebae already described 

 from rats and mice possess hyaline pseudopodia. 



Endamoeha coli (Losch) from man, on the other hand, differs 

 remarkably from these amoebae in this regard. Dobell and 'Connor 

 (1921) stated that in the change of shape of Endamoeba coli, without 

 evident progression (fig. on their pi. 1), "no sharp line of demarcation 

 separates the ectoplasm and endoplasm, and the formation of large, 

 clear, blade-like pseudopodia — so characteristic of Endamoeba histo- 

 lytica — is never seen." 



One of the distinguishing characteristics between Endamoeba coli 

 and Councilmania. laflcuri (Kofoid and Swezy, 1921) is this difference 

 in formation of pseudopodia, hyaline pseudopodia being the type 

 possessed by Coiincilmania la.fleuri. It therefore seems quite evident 

 that in this one respect alone there is sufficient differentiation to war- 

 rant drawing a distinction between Endamoeha coli and the amoebae 

 of the rat and mouse. 



The formation of pseudopodia of CouncUmania muris and of 

 Councilmania decumani can be described most satisfactorily by divi- 

 sion of their movements into two types : first, that during progressive 

 movement and second, that during attachment to the substrate. In 

 both types of movement the pseudopodia are characteristically hyaline. 



