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



As to the power, spoken of by Mr. Carter, possessed by the 

 ectosarc {sic) of passing through the pellicula, it will be seen, 

 on reference to my paper in the ' Annals ' for May (p. 370), 

 that I distinctly point out this feature, and endeavour to prove 

 by it, for reasons there assigned, that the ectosarc is gradually 

 dissolved, as it were, when pierced by a newly projected mass of 

 sarcode in the shape of a pseudopodium, in such a manner as to 

 envelope a portion of the old ectosarc. Mr. Carter's figure 

 (Annals for July, pi. 3. fig. 4) diagrammatically represents this 

 condition, and, to my mind, clearly proves one of two things, — 

 either that a new portion of ectosarc is instantaneously produced 

 on the contact of the endosarc with the surrounding medium, 

 or that, where such pseudopodia are projected, their characters 

 must be of a different kind from the rest of the structure — an 

 inference which is obviously not tenable for a moment. Lastly, 

 I am unable to see that, by calling in to our aid any such pro- 

 cess as secretion from the surface of the newly projected portion 

 of sarcode, any more satisfactory explanation of the phenomenon 

 is afforded ; for it is obvious that, for every quota of ectosarc 

 secreted, an equivalent quota would have to be re-absorbed, 

 otherwise the whole body would rapidly be converted into ecto- 

 sarc ; whilst, assuming the process to be one of alternate secre- 

 tion and absorption, the reciprocal convertibility of the ectosarc 

 and endosarc for which I contend would be admitted a priori^. 

 If not reciprocally convertible one into the other, as I have de- 

 scribed, how is it that the contractile vesicle is sometimes single, 

 sometimes multiple, in the same portion of the body — the 

 multiple vesicles now performing their office separately and in- 

 dependently of each other, now coalescing with one another, so 

 as to undergo their contraction in the shape of a single cavity ? 

 How is it that we constantly see a tentative double or multiple 

 contractile vesicle — that is to say, two or more cavities separated 

 from each other only by the most delicate films of protoplasmic 

 substance which forms the partition -walls, these walls permitting 

 the union of the contents on either sidt^^ not through a minute 

 specialized aperture, but in a similar manner to the coalescence of 

 two soap-bubbles ? whilst on the next occurrence of distention 

 at the same spot the contractile vesicle may appear in the shape 

 of a single large cavity without supplementary ones. How is it 

 that an Amceha may be lacerated so as to form two or more por- 

 tions, each of which almost instantaneously presents, at every 

 portion of the surface, the same appearances as existed prior to 



* Mr. Carter speaks explicitly on this point. He says (Annals for July, 

 p. 118), " That the diaphane, therefore, should pass into the pelUcula, or 

 the pellicula be secreted by the diaphane, seems untenable." 



