224 Dr. Wallich on the Amoebfe. 



In such a case it is obvious that onlj the granules on the upper 

 or free aspect of the sac would be carried onwards, that, having 

 arrived at the most advanced pointy they would be, as it were, 

 deposited, and remain stationary, as woidd also that portion of 

 the sac on which they rested, until the rest of the mass should 

 have again flowed over them, causing them now to ajypear at 

 the posterior extremity, when they would once more he urged on 

 as hefore. 



" The same explanation will, I think, be found to hold 

 good in some families, as, for instance, the Foraminifera. The 

 essential attributes of sarcode, extensibility and contractility, 

 coupled with the polymorphism evident on every example in 

 which definite form is not partially maintained by the presence 

 of a shell or test, necessarily involve the power of retracting 

 as well as projecting these processes, whereas the tenacity of 

 the substance is not such that a pseudopodium once projected 

 can be retracted towards the body in the same way that a 

 rope thrown forward from a given point can be hauled in 

 again, inch by inch. In the pseudopodium of Amoeba, as also 

 in the attenuated filaments of the Foraminifera, or the still more 

 subtle filaments of Acanthometra or Euglypha, the process is 

 the same, and is brought about by the reciprocal outward and 

 inward flow of the sarcode substance ; and thus the granular 

 particles are merely the passive exponents of a vital force 

 which exists quite independently of them. Hence, with all 

 deference to such an authority as Prof. Schultze, I would still 

 regard the circulation of granules in the Ehizopods as a PSEU- 

 DOCYCLOSIS, analogous, I grant, in appearance but not in 

 origin to the cyclosis observable in certain vegetable cells, as, 

 for example, Tradescantiay — Ann, & Mag. Nat. Hist. Nov. 

 1863, pp. 331, 332. 



" In the Amoeban Rhizopods in general, without any excep- 

 tion, whether naked or testaceous, their protoplasmic substance 

 is differentiated into an anterior and posterior portion." — 

 Ann. & Mag. Nat. Hist. Nov. 1863, p. 333. 



" Now contractility is the inherent property of protoplasm, 

 but not till it has become consolidated to a certain point ; and 

 this consolidation does not take place within the substance 

 itself, but only at the surface *. If we take the example of an 

 ordinary contractile substance the process is to all intents the 

 same. Thus caoutchouc, when oozing from the parent tree, is 

 not contractile but a semifluid viscid mass. So is the sarcode 



* The formation Avithiii the general mass of the body -substance of 

 ectosarc in the case of vacuolar cavities, or the contractile vesicle or vesi- 

 cles, as ■will be seen in a former extract, does not constitute an in- 

 trinsically originating process, but dependent, as in the true outer ectosarc 

 layer, on the presence of, or contact with -water. 



