GENUS AMCEBA— AMCEBA PROTEUS. 33 



names of all forms of Amoeba previously described by others, including 

 the one first discovered, the little Proteus of Rosel. 



In the earlier description of Amoeba princeps, Ehrenberg says it is four 

 times larger than the Proteus, meaning the Proteus diffluens of Midler and 

 his own Amoeba diffluens, but not the Proteus of Rosel; for this, according 

 to the actual representation of the latter, is four times larger than Amoeba 

 princeps, and sixteen times larger than Amoeba diffluens, according to the 

 measurements of these given by Ehrenberg. 



In the remarks on Amoeba princeps, in the Infusionsthierchen, Ehren- 

 berg says "it is true that Rosel described a larger species of Proteus of 

 which the dimension accords with this, but the blunt processes, of the species 

 occurring in Berlin, do not agree well with those of Rosel's figures, but 

 rather approximate those of larger individuals of Amoeba diffluens." 



It is natural to suppose that an Amoeba discovered by the earliest 

 microscopic observers would be one of the more common large forms, and 

 that such was the case appears to be fairly proved by figures and descrip- 

 tions. 



Rosel, in referring to one of his figures of the little Proteus, remarks 

 that in its natural size it looked like A. Now, this figure A represents the 

 animal in its quiescent state, in globular form, and the figure measures just 

 four fifths of a line. No Amoeba has since been recorded, in the same 

 condition, so large as this, and it is not unfair to suppose that the figure is 

 somewhat exaggerated, which could readily occur in absence of the accurate 

 means of measurement which came subsequently into use. 



Rosel refers to his having held his little Proteus at rest with a pointed 

 feather, which is alone sufficient to prove that he had under his observation 

 one of the largest forms of Amoeba. 



In size, according to the actual measurements given, Rosel's Proteus 

 is as much larger than Amoeba princeps as this is than Amoeba diffluens. 



In all other characters ascribed by Ehrenberg to Amoeba princeps, it 

 appears to the writer to agree with the Proteus of Rosel, and this without 

 doubt better than does the Amoeba diffluens as described by Ehrenberg. 



Amoeba princeps is said by the latter to be yellowish, while the Amoeba 

 diffluens is said to be clear as water. Though Rosel says nothing of the 

 color of the Proteus, his figures, carefully colored, exhibit the granular 



3 EHIZ 



