no 



I. IJIMA. 



To all appearance the villous knob is naked, i.e., devoid of an external en- 

 veloping membrane The same can not be said of the main body. An indubit- 

 able, double-contoured membrane is indeed not directly demonstrable in either 

 fresh or prepared specimens under ordinary circumstances. 'Ihe contour-line of 

 the main body appears sharp but is simple. Nevertheless, it often happens after 

 death that the entire Amœba is blown out into a thin-walled Vesicle by the ex- 

 cessive enlargement of the vacuoles contained, then to remain in that state for a 

 considerable length of time; giving an impression as if the tension of a special 

 superficial layer resisted its speedy bursting. Ajrain, should the animal be left 

 for some time in a dilute solution of acetic acid, the fluid imbibed into the sar- 

 code frequently accumulates itself in the form of vacuoles just under the surface 

 and heaves up from below a pellicle in a pustule like manner (fig, 7). These 

 appearances have led me to infer that a thin elastic layer of a firmer consistency 

 than the internal sarcode covers the whole surface, interrupted only at one spoj 

 by an opening through which the pseudopodia-producing ectoplasm is protruded 

 knob-like into the exterior. This would be exactly the sani ; state of things as 

 has been described in certain near allies of the present species, e. g., in Amœba 

 fluida by Greeff,* in the genus fîagiophrySs by Archest and Penard'I, a con- 

 dition that leads over to that seen in the soft-shelled, monothalamoas and 

 monostoniatous Rhizopods. In Am. fluida the membrane should be thicker and 

 more distinct than iu the present species. 



The main body is not altogether incapable of changing its form but unlike 

 its known nearest allies A m. villosa and Am. fluida, the motion is so slow and 

 limited in extent that it requires close observation to perceive it. The shape 

 may change from spherical into ellipsoidal or vice vers I and at times assume a 

 somewhat irregular outline. In one case I have observed a slow wave-like 

 movement of the surface, so that the latter presented a slightly verrucose appear- 

 ance (fig. 1). A " flowing " motion of the sarcode or such active transformation 

 of the body into lobate pseudopodia as is ascribed to Am. villosa or Am. fluida, 

 was never noticed. On the contrary, the various enclosures retained tolerably 

 constant relative positions all the while (luring observation. It seemed as if the 



* Gbeeff : loc. cit., p. 375. 



t Aechek : Quart. Jour. Micr. Sci. Vol. XI. 



Î PiCNAjtD : Mém. Soc. Ph.vsiq. H. N. Genève, T. XXXI, No. 2. 



