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



more supplementary vesicles (the analogues of the sinus-system 

 of Paramecium, &c., according to that author), between the sup- 

 plementary vesicles and the primary contractile vesicle, or between 

 the principal one and the exterior, are borne out by the facts he 

 thus describes and their illustrative figures, it appears to me 

 that no facts could more directly negative the conclusions at 

 which he has arrived, — in the first place, from the circumstance 

 of " the small sinuses which surround " the primary vesicle be- 

 ing at all capable of isolation " from the rest of the sarcode 

 and from each other/' and in the second, because the efi'ect of 

 iodine being to cause sarcode to contract and become consoli- 

 dated, unless it can be shown that, besides mere reduction in 

 bulk, such an increase of contractile power is secured as would 

 prevent a determinate orifice from yielding under the tension to 

 which the wall of the vesicle is subject, the retention of the 

 cell-form, at the same time that the connecting sinuses are de- 

 stroyed, is only reconcilable with one supposition, namely, that 

 every portion of the vesicular wall is of uniform and unbroken 

 composition. For I must repeat that since the changes of posi- 

 tion usually undergone by every detached supplementary vesicle 

 are as fortuitous as the shape of the body or the size of the 

 pseudopodia, the difficulty of conceiving that these vesicles should 

 revert to the precise point at which the excretory aperture is 

 assumed to exist, so as to ensure that exact coincidence between 

 the latter and their own excretory orifices which is essential to the 

 stability of Mr. Carter's theory, must be regarded as insuperable. 



I must also call attention to the difficulty of comprehending 

 in what manner the prehensile power of the villi is effected, if 

 the pellicula, which Mr. Carter declares to have no prehensile 

 power {' Annals,' July 1863, p. 32), save when exercised under 

 the " instinct" of the creature, invests the villous organ. It 

 is clear that Mr. Carter assumes that it does so ; otherwise he 

 would not have made use of the expression, that there is an 

 " aperture through the diaphane and pelhcula " at that particular 

 portion of the body. 



Lastly, without offering any opinion on the question of " in- 

 stinct," as here introduced, I have no hesitation in saying that 

 the prehensile action observable in the villi of Amoeba villosa is 

 not of a grasping kind, as if they were minute pseudopodia, but 

 distinctly adhesive and residing at the immediate surface. As 

 stated by me [' Annals,' April, p. 288), so powerful is the pre- 

 hensile action, that at times the villi become stretched beyond 

 their endurance when the animal is moving. When this takes 

 place to an inordinate degree, they are rent asunder, the torn 

 extremity next the body starting back, at the instant of rupture, 

 as if resilient. 



