ON A NEW RHIZOPOD PARASITE OF MAN. 



89 



villi-like pseudopodia were sometimes found emanating in irregular distribution 

 from the general surface (fig. 5, a & c), what might be expected to occur in im- 

 mature individuals so long as these would be naked and the ectoplasm not con- 

 centrated into a knob. 



It sometimes happens in life that the villiforrn pseudopodia are entirely re- 

 tracted. The knob then presents a smooth surface (fig. 5, e), as it does always 

 when acted upon by reagents (fig. G). Otherwise it is beset with shorter or 

 longer pseudopodia as the case may be. "When short, the pseudopodia are gene- 

 rally conical in shape and comparatively thick though minute (fig. 1). By 

 focussing up and down the microscope, it was easy to observe the knob-surface 

 closely studded over with them. "When fully extended (fig. 2), they may reach 

 5 fi in length and are extremely fine, broadest at base an 1 thinned out towards 

 end. They then seem to radiate forth in tolerably straight course. Although I 

 do not remember having ever seen them branch or anastomose, yet I do not feel 

 myself sufficiently warranted to exclude the possibility of such occurrence. The 

 actual movement of the pseudopodia, whether molecular or otherwise, could not 

 be watched in continuous succession, what is sufficiently accounted for by the 

 slowness of motion combined with the fineness and the hyaline nature of the 

 pseudopodia. On the other hand, by examining the same living object at inter- 

 vals of several minutes, I could plainly observe, under favorable circumstances, 

 the variation in the degree of contraction or elongation of the filamentous struc- 

 tures under consideration,— evidence enough that the-e are to be seen in the light 

 of pseudopodia and not of immobile villi. The same view has been put forward 

 by Greeff* for the identical structures, of Am. fluida. 



The so-called villous knob passes usually, though not always, insensibly into 

 the main body. Not unfrequently, however, there were cases in which the two parts 

 Avere separated externally by a tolerably sharp line of demarcation (fig. 3). This 

 was brought about by the presence of a shallow ring-groove surrounding the 

 basis of the knob. The appearance then is as if cither the knob-base has just 

 slightly sunk into the main body or the latter has elevated itself in a low wall 

 around the former. This is without doubt only a temporary condition arising 

 from a certain state of contraction of the sarcode. 



* Gretsff : Biol. Centrali]. Bd. XII, p. 377., 



