Dr. G. C. Wallich on an undescribed Indigenous Amoeba. 369 



resisted pressure in a manner that showed its strength and at 

 the same time the probable absence of any aperture through 

 which its contents, if not forming part and parcel of itself, 

 might have escaped. In short, disruption did not take place 

 until after the glass cover in use (measuring -008 of an inch in 

 thickness) had been broken. The wall then exhibited very dis- 

 tinct angular folds and a clear membranous outline, but of too 

 great tenuity to admit of the measurement of its thickness. In 

 this specimen the nucleus, probably owing to displacement by 

 the pressure, occupied a position at the centre of the body — 

 no contractile vesicle or larger granular mass being present, but 

 several vacuoles being scattered through its substance. 



One of the most remarkable amongst the novel and varied 

 characters of these Amoeba consists in the vesicle in which the 

 true nucleus is contained having been found to be distinctly 

 membranous in some individuals. In the figures appended to 

 my paper in the last Number of the ' Annals/ I endeavoured to 

 show the definite appearance of the vesicular chamber of the 

 nucleus ; but at that time I had no idea of the peculiarity thereby 

 indicated, nor did I become aware of it, or indeed believe in it, 

 until I had seen several nuclei with their vesicular covering com- 

 pletely isolated from the main body by means of the compressor. 

 The fact, startling as it seems, is nevertheless certain, that in 

 these specimens the nucleus was contained in a distinct mem- 

 branous cell of its own, and that this cell admits of perfect 

 isolation without undergoing rupture. The cell-wall was sphe- 

 rical in its extruded state, perfectly hyaline, tough, and resisting, 

 and forming irregular folds under augmented pressure, as shown 

 in figures 7 and 7b, — a clear nucleolus, as before described, being 

 visible in the interior of the granular nucleus, and the space be- 

 tween the nucleus and cell-wall being occupied by a still more 

 attenuated granular protoplasm. In contradistinction to this, 

 the multiple nuclei, already spoken of, had neither investing 

 membrane nor nucleolus. Can it be that the one phase repre- 

 sents the germ-cell, and the other the sperm-cells ? 



Another fact is deducible from the appearances presented by 

 the sarcode-substance of the largest of these Amoeba. The rush 

 of granules does not follow upon a previous contractile effort 

 exercised at the posterior portion. As the animal progresses, 

 occasionally altering its course, there are periods during which 

 perfect quiescence is maintained by the granules ; and the rush 

 or flow of these seems to take place, as it were, to fill up the 

 vacuum engendered by the sudden projection of a portion of the 

 ectosarc in the shape of a pseudopodium. Hence it would ap- 

 pear that motion is dependent on the contractile power of the 

 external sarcode-layer ; and that the endosarc only passively par- 



