222 Dr. Wallich on the Araoebse. 



structure, of forming extempore orifices for the inception or 

 extrusion of food-particles, &c., may be witnessed in these 

 specimens in a very singular manner, and one which, as far 

 as I am aware, has not hitherto attracted attention. I allude 

 to the projection of the ectosarc from some area of the general 

 surface in the form of a hemispherical 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 endo- 

 sarc and other granular contents 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 pseudopodial cavity not being established until the 

 completion of this process. Whilst it is progressing, the 

 endosarc-granules seem to rush round a corner into the cavity, 

 the corner gradually receding, so to speak, and ultimately 

 being altogether obliterated. 



"From these facts it is obvious that the ectosarc and endo- 

 sarc are not 'permanent portions of the Protean structure^ hut 

 mutually convertible one -into the other ; and that it is an essen- 

 tial feature of sarcode that, whilst the outer layer for the time 

 being becomes, ipso facto, instantaneously differentiated into 

 ectosarc, the same layer reverts to the condition of endosarc 

 under the circumstances just described. 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." — Ann. & Mag. Nat. Hist. 

 May 1863, pp. 369, 370. 



" In my experience the contractile vesicle does not make its 

 appearance either in the lowest order" (according to my 

 classification), " viz. the Herpnemata, or second order of Pro- 

 TODERMATA, but occurs for the first time in the third order, 

 viz. the Proteina, in which I associate the Actinophryna, 

 Lagenidse, and Amcebina. In the third order both nucleus 

 and contractile vesicle are invariably present, though naturally 

 difficult of detection in the testaceous genera. The latter 

 organ, however, in so far as my experience of living repre- 

 sentatives of nearly every important form enables me to arrive 

 at a correct opinion on the subject, ought not to be regarded 

 as a definite-walled contractile sac, distinct in composition 

 from the rest of the protoplasmic matter, but simply as a 

 specialized vacuolar cs^Viij, formed out of a jportion of ectosarc.^'' 

 — Ann. (& Mag. Nat. Hist. June 1863, p. 439. 



" In Aonceba, the true ectosarc appears to be nothing more 

 than the outer layer of sarcode (for the time being) consoli- 

 dated by contact with external influences, its thickness being 

 dependent on the length of time these influences continue 



