RECENT MEMOIRS ON FRESHWATER RHIZOPODA. 345 



perceive a nucleus, but they noticed in the yellow form 

 several contractile granules. 



From the body radiate everywhere around the broad, 

 blunt, slightly conical, pseudopodia, in length reaching about 

 a half of the body-diameter, and like the border, they con- 

 sist of a perfectly homogeneous, quite clear, glassy-looking, 

 plasma. In most, if not all, of the examples of the green 

 form the whole superficies (including the pseudopodia), was 

 covered by peculiar protoplasmic, hair-like prolongations, 

 resembling the partial one of Amoebae, but not the same; no 

 movement was perceptible in these minute villi. Very pecu- 

 liar is the mode of retraction of the pseudopodia : one about 

 to become drawn in abruptly alters its figure — its usually 

 smooth surface becomes uneven and irregularly hollowed out 

 here and there — whereupon it quickly flows back into the 

 body-mass. The whole process conveys the impression as if 

 the pseudopodium had suddenly lost its turgidity. 



A further distinction between the two forms is seen in the 

 mode of motion. The green animals lay mostly at rest as 

 more or less regular balls, and only these, with their not 

 numerously projected pseudopodia, showed a slow forward or 

 backward movement. It was quite different with the yellow 

 animals. These not only moved with comparative rapidity 

 by aid of their quickly projected, mostly numerous pseudo- 

 podia, but even their body-mass took an active share in 

 locomotion, similarly to that of Amoeba. In this form the 

 authors saw a division and separation into two of a single 

 individual. 



The authors suggest the possibility that their green form 

 might be one and the same thing with the form described 

 as a variety of Amoeba radiosa, by Auerbach.^ But the fact 

 that in that form the granulated contents, completely filling 

 the body-mass up to the very margin, and passing even into 

 the pseudopodia, is regarded by the authors as speaking 

 very strongly against the identity of that with this form, in 

 which latter, such never takes place. 



Leptophrys cinera (fig. 19), L. elegans, Hertwig et Lesser 



(fig. 20). 



The forms for which the authors establish a genus under 

 the above name belong indeed to the most delicate-looking 

 of Sarcodina. Their protoplasm is very pellucid, thickly 

 permeated with vacuoles of small and nearly equal size, and 

 non-contractile ; the interspaces are filled with very minute 



^ Auerbach : " Ueber die Enizelligkeit der Amceben " iu ' Zeits. f. Wiss. 

 Zool.,' Bd. vii, p. 401. 



