1885.] 



MICROSCOPICAL JOURNAL. 



191 



notion is dependent on the contractile 

 power of the external sarcode-layer, 

 and that the endosarc only passively 

 participates in it. If this view be 

 correct, it involves a very important 

 consideration ; for it proves that the 

 old German doctrine of a "primary 

 contractile mucus" is essentially cor- 

 rect, and that the circulation is not 

 dependent, even in part, on the alter- 

 nate expansion and collapse of the 

 contractile vesicle. Further than this, 

 it affords the strongest confirmation 

 of the high degree of "differentia- 

 tion" existing between the endosarc 

 and ectosarc of the amoeban group. 

 'The mysterious faculty, resident 

 in the latter portion of the structure, 

 of forming extejttpore orifices for the 

 inception or extrusion of food-parti- 

 cles, etc., may be witnessed in these 

 specimens in a very singular manner, 

 and one which, so far as I am aware, 

 has not hitherto attracted attention. 

 I allude to the projection of the ecto- 

 sarc from some area of the general 

 surface, in the form of a hemispheri- 

 cal mass with a broad base, only a 

 very small portion of the original 

 contour line seeming to give way at 

 first, so as to admit of the passage of 

 the endosarc and other granular con- 

 tents into the newly projected part, 

 but its entire floor appearing to be 

 gradually dissolved, as it were, and 

 free communication between the main 

 body and the new pseudopodiil cavity 

 not being established until the com- 

 pletion of the process. Whilst this 

 is progressing, the endosarc-granules 

 seem to rush round a corner into the 

 cavity, the corner itself gradually re- 

 ceding, so to speak, and being idti- 

 mately altogether obliterated. From 

 these facts it is obvious that the ecto- 

 sarc and endosarc are not permanent 

 portions of the protean structure, but 

 are mutualh' convertible one into the 

 other ; and that it is an essential feat- 

 ure of sarcode that, while the outer 

 layer for the time being becomes, 

 ipso facto ^ instantaneously differenti- 

 ated into ectosarc, the same layer re- 

 verts to the condition of endosarc 



under the circumstances just de- 

 scribed.* In the latter part of the 

 process — that is, the reversion to the 

 condition of endosarc — the action is 

 by no means so instantaneous as when 

 the converse takes place. In the 

 actinophryans, both processes are, 

 comparatively speaking, slow.' — 

 (Further Observations on an unde- 

 scribed Indigenous Amceba i^Amceba 

 Villosa^ Wal.), by Surgeon-Major 

 Wallich, M. D., Annals and Mag. 

 Nat. Hist., May, 1863.) 



' The conversion of endosarc into 

 ectosarc I regard as analogous in 

 character, if not actually identical, 

 with coagulation ; the effect being 

 produced by the mere contact of 

 sarcode with the medium in which 

 the animal resides, whilst the con- 

 verse process constitutes an inherent 

 vital function of the animal proto- 

 plasm. Should this view be admis- 

 sible, we have presented to us a phe- 

 nomena bearing, in a most important 

 degree, on the general question of 

 development, and one which, I ven- 

 ture to affirm, is far more largely en- 

 gaged in the production of specific 

 type, not only amongst the lower but 

 also amongstthe higher orders of be- 

 ing, than we have heretofore been in- 

 clined to allow. I allude to the recip- 

 rocal action of physical and vital 

 forces.' (On the Value of the Dis- 

 tinctive Characters in Amoeba. By 

 the same author. Annals <& Mag. 

 Nat. Hist., Aug., 1863.) 



' It is only necessary to watch a 

 specimen of Amoeba carefully to be- 

 come convinced that the appearance 

 of a returning as well as an advancing 

 stream is illusory. The stream, it 

 will be observed, is invariably in the 

 direction of the preponderating pseu- 

 dopodial projections. The particles 

 simply flow along with the advancing 

 rush of protoplasm. There is no re- 

 turn stream, but only the semblance 

 of one engendered by one layer of 

 particles remaining at rest while 



•The conclusion here arrived at and the facts on 

 which It is based have very recently been published as 

 new and original by Herr Oriiber. (See jfourn. Royal 

 Micr. Soc., April, i885, pp. aOo-i.) 



