AMCEBA 



231 



C, Amteha proteus, a. living specimen, showing large irregular pseudopods, 

 nucleus (»k), contractile vacuole (c. vac), and two food vacuoles iy, vac), each 

 containing a small infusor (see p. 261) which has been ingested as food. The 

 letter a. to the right of the figure indicates the place where two pseudopods have 

 united to enclose the food vacuole. The contr.^ctile vacuole in this figure is 

 supposed to be seen through a layer of granular protoplasm, whereas in the 

 succeeding figures (D, E, arid G) it is seen in optical section, and therefore 

 appears clear. 



D, an encysted Amoeba, showing cell-wall or cyst (cy), nucleus (««), clear con- 

 tractile vacuole, and three microscopic plants (diatoms) ingested as food. 



E, Aiiiteba proteus, a living specimen, showing several large pseudopods {,psd), 

 single nucleus («k) and contractile vacuole (c. vac), and numerous food-particles 

 embedded \n. the granular endoplasm ( X 330). 



F, nucleus of thesame after staining, shownig a ground substance of achromatin, 

 containing deeply-stained granules of chromatm, and surrounded by a distinct 

 membrane ( X loio). 



G, Amceba verrucosa, living specimen, showing wrinkled surface, nucleus (««), 

 large contractile vacuole (t. vac), and several ingested organisms (X 330). 



H, nucleus of the same, stained, showing the chromatin aggregated in the centre 



(X 1010). 

 I, Amceba proteus, in the act of multiplying by binary fission (X 500). (From 



Parker's Biology : A, B, E, F, G, and H after Gruber ; C and I after Leidy ; D 



after Howes.) 



Examined under the high power (Fig. 67), the Amceba 

 appears like a httle shapeless blob of jelly, nearly or quite 

 colourless, and closely resembling a colourless blood cor- 

 puscle or leucocyte of one of the higher animals (p. 105). 

 The central part of it, or endop/asm, is granular and semi- 

 transparent — something like ground-glass — while surround- 

 ing this inner mass is a border of perfectly transparent and 

 colourless substance — the ectoplasm. 



One very noticeable thing about the Amoeba is that, like 

 the leucocyte, it is never of quite the same form for long 

 together, owing to the protrusion of pseudopods {psd), 

 by means of which it creeps along slowly. The occur- 

 rence of amoeboid movements is alone sufificient to show 

 that it is an organism, or ' living thing, and no mere mass 

 of dead matter. Moreover, it consists of protoplasm 

 and contains a nucleus (C — H, nu), which is rendered more 

 apparent by staining and consists of chromatin and achro- 

 matin. The Amceba is therefore a cell (compare p. 106). 



A very important difference is thus at once seen between 

 the Amoeba and the frog ; the Amoeba is unicellular, i.e. it 

 consists of a single cell, while the frog is, as we have seen 



