140 Dr. G. C. Wallich on the Value of 



hyaline and brilliant globule presented to view when observed in 

 its state of greatest distention. The transition, however, is gra- 

 dual, and leaves no room for doubt on this head. Sometimes the 

 diastole* is altogether confined to the main cavity of the organ. 

 When this happens, the central diaphanous space which shortly 

 presents itself increases slowly in dimensions, whilst pari passu 

 the boundary-wall becomes thinner, the villi grow shorterf, and 

 the opacity is exchanged for an almost crystalline transparence. 

 In this condition, the remains of the little villi can be faintly 

 detected, under a sufficient magnifying power, as minute spots, 

 distributed sparsely and unequally over the surface of the 

 vesicle. But no trace of a double outline is visible, even under 

 the highest power of the microscope ; nor does its boundary wall 

 approach more closely to the appearance of distinct membrane 

 than the boundary wall of an oil-globule. Indeed, but for the 

 scattered papillse on its periphery, it would be absolutely hyaline 

 throughout, and barely distmguishable from a solid globule of 

 sarcode. In this, its fully distended state, no supplementary 

 vesicles are evolved from any portion of its surface. During the 

 systole, the appearances are reversed in their order, and take 

 place in a much shorter period — the hyaline clearness becoming 

 first destroyed, and the faint spots growing, as it were, into a 

 crowd of villi, until finally the whole mass resumes its pristine 

 aspect. But now and then the systole seems to be checked 

 before completion, and the diastole recommences without entire 

 obliteration of the cavity. Again, instead of the diastole origi- 

 nating at a single point, sometimes from two to twenty minute 

 globules start into existence around or near that point, and 

 cover a space considerably in excess of that occupied by the col- 

 lapsed primaiy contractile vesicle. These globules are cavities 

 formed within the villi, which thus become temporarily con- 

 verted into cseca, admitting of distention to a certain point, and 

 then either bursting into each other or into the primary cavity, 

 as the case may be ; whilst at other times one or two, but very 

 rarely more, of the supplementary vesicles thus formed become 

 altogether detached, after the fashion of a soap-bubbie given off 

 from a pipe J, and circulate amongst the rest of the particles 

 within the endosarc of the Amoeba. When this occurs, I have 



* Although the organ in question bears no analogy to the heart of the 

 higher animals, as it contracts and expands rhythmically, the terms diastole 

 and systole may be employed without impropriety, in order to distinguish 

 the action more clearly from that of the ordinary vacuoles. 



t An analogous effect is produced when a caoutchouc capsule, the wall 

 of which is tuberculated and opaque in its unexpanded state, is inflated 

 until the entire surface assumes a homogeneous and semidiaphanous 

 appearance. 



X Mr. Carter suggests this simile in describing the disengagement of 



