GENERAL CHARACTERS 3 



some formed of ectosarc only, others containing a core of endosarc. 

 The larger bodies in the endosarc are mostly food-particles (X 300). l 



B. The same species, killed and stained with carmine to show the 

 numerous nuclei (mt) (X 300). 



C. Amceba proteus, a living specimen, showing large irregular 

 pseudopods, nucleus (mt), contractile vacuole (c.vac), and two food 

 vacuoles (f.vac), each containing a small infusor (see Lesson X.) which 

 has been ingested as food. The letter a to the right of the figure in- 

 dicates the place where two pseudopods have united to inclose the food 

 vacuole. The contractile vacuole in this figure is supposed to be seen 

 through a layer of granular protoplasm, whereas in the succeeding 

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

 clear. 



D. An encysted Amceba, showing cell-wall or cyst (cy\ nucleus (mi), 

 clear contractile vacuole (c.vac), and three diatoms (see Lesson XIV. ) 

 ingested as food. 



E. Amoeba proteus i a living specimen, showing several large pseudo- 

 pods (psd), single nucleus (nu), and contractile vacuole (c.vac), and 

 numerous food particles imbedded in the granular endosarc ( X 330). 



F. Nucleus of the same after staining, showing a ground substance or 

 achromatin, containing deeply-stained granules of chromatin, and 

 surrounded by a distinct membrane (X 1010). 



G. Amceba vemtcosa, living specimen, showing wrinkled surface, 

 nucleus (mi), large contractile vacuole (c. vac) and several ingested 

 organisms (X 330). 



H. Nucleus of the same, stained, showing the chromatin aggregated 

 in the centre to form a nucleolus (X 1010). 



I. Amceba proteus, in the act of multiplying by binary fission 

 (X5oo). 



(A, B, E, F, G, and H after Gruber ; c and I after Leidy ; D after 

 Howes.) 



shapeless blob of jelly, nearly or quite colourless. The 

 central part of it (Fig. i, A, c, and E) is granular and semi- 

 transparent something like ground glass while surround- 

 ing this inner mass is a border of perfectly transparent and 

 colourless substance. So clear, indeed, is this outer layer 

 that it is easily overlooked by the beginner, who is apt to take 

 the granular internal substance for the whole Amoeba. If 

 in any way the creature can be made to turn over, or if a 

 number of specimens are examined in various positions, 



1 A number preceded by the sign of multiplication indicates the 

 number of diameters to which the object is magnified. 



B 2 



