450 Dr. G. C. Wallich on Amoeba villosa 



should define the meaning of a term which has been so indis- 

 criminately applied to the most widely difiering portions of the 

 Rhizopodal structure. Miiller* uses the term at one time to 

 signify the central or primordial chamber of the siliceous shell 

 of the Polycystina, and at another to distinguish the more 

 brilliantly coloured contents of that chamber from the otherwise 

 identical sarcode of those portions of the structure that are sub- 

 sequently developed. He also employs it in defining the central 

 point of union of the siliceous framework of Acanthometra. Stein, 

 it would appear, applies it to the entire " medullary " portion of 

 Adinophrys oculata, which I regard as nothing more than a 

 small form of A. Eichhornii ; whilst Carter and Carpenter em- 

 ploy it in its only legitimate sense — that is, to denote a perma- 

 nent part of the protoplasmic substance, more or less distinctly 

 granular when fully developed, having a definite outline, con- 

 tained within a definite-shaped cavity, often seen to undergo 

 binary division whilst the rest of the body still remains entire, 

 and apparently serving some important purpose in the reproduc- 

 tion of the individual. In the latter sense the term is used by 

 me in these pages. 



In A. Eichhornii, the subdivision of the nuclear body seems to 

 keep pace with the extraordinary degree of vacuolation to which 

 reference has already been made. For instead of meeting with 

 it as a simple aggregated mass such as we find in Amoeba, it is 

 split up into numerous minute spherical masses, each of which 

 presents the characters of a true nucleus on a reduced scale. 

 These multiple nuclei are distributed, here and there, through 

 the protoplasm — each occupying a spherical cavity which is 

 completely filled up by the granular matter, and quite distinct 

 in outward appearance from the polygonal soap-bubble-like mass 

 of which the rest of the body is constituted. Facts are, how- 

 ever, still wanting to show whether the subdivision of the nuclei 

 in A. Eichhornii is due to a repetition of the process which brings 

 about the double or treble nucleus of the Amcebce, or whether it 

 is to be regarded as a normal and original condition in this form. 

 If normal, it would certainly furnish a substantial character 

 whereon to build a specific distinction. (See figs. 1 and 2.) 



The hyaline transparence of the form under notice is admi- 

 rably suited for affording an unobstructed view of the structure 

 and mode of action of the contractile vesicles. As already 

 stated, these vary in number. I have counted as many as five in 

 the same specimen, all of which maintained a regular but per- 

 fectly independent rhythmical action. They never change their 

 position, nor do they produce any appreciable efiect on the cellular- 



* Uber die Thalass. Polycyst. und Acanthom. des Mittelmeeres. Berlin, 



1858. 



