MICROSCOPIC FORMS OF ANIMAL LIFE. 



15 



streams and ponds, vegetable infusions, etc., than the Amoeba (Fig. 289); 

 a creature which cannot he described by its form, for this is as changeable 

 as that of the fabled Proteus, but may yet be definitely characterized by 

 peculiarities that separate it from the two groups already described. 



The distinction between ' ecto- 



Fio. 288. , , . , , . , 



sarc and endosarc is here 

 clearly marked, so that the 

 body approaches much more 

 closely in its characters to an 

 ordinary 'cell' composed of 

 cell- wall and cell-contents. It 

 is through the ' endosarc 7 

 alone, EIST, that those colored 

 and granular particles are dif- 

 fused, on which the hue and 

 opacity of the body depend ; its 

 central portion seems to have 

 an almost watery consistence, 

 the granular particles being 

 seen to move quite freely upon 

 one another with every change 

 in the shape of the body; but 

 its superficial portion is more 

 viscid, and graduates insensibly 

 into the firmer substance of 

 the 'ectosarc.' The ectosarc, 

 EC, which is perfectly pellucid, 

 forms an almost membranous 

 investment to the endosarc; 

 still it is not possessed of such 

 tenacity as to oppose a solution 

 of its continuity at any point, 

 for the introduction of alimen- 

 tary particles, or for the ex- 

 trusion of effete matters; and 

 thus there is no evidence, in 



Clathrulina eleqans : A, complete organism ; B, swarm- A vn ^tin n n c\ i fc i m m &{\ i n f o 

 spore, showing nucleus, n, and Ltwo contractile vesicles AmCBOtt ana ItS immediate 



near its opposite end. allies, of the existence of any 



more definite orifice, either oral 

 or anal, than exists in other 

 Ehizopods. The more advanc- 

 ed differentiation of the ecto- 

 sarc from the endosarc of 

 Amoeba, is made evident by 

 the effects of re-agents. If an 

 Amoeba radio sa be treated with 

 a dilute alkaline solution, the 

 granular and molecular endo- 

 sarc shrinks together and re- 

 treats towards the centre, 

 leaving the radiating exten- 

 sions of the ectosarc in the 

 condition of csecal tubes, of 



Diagrammatic representation of Amoeba protcus; E c, which the Walls are not Soluble 

 ectosarc; EN, endosarc; cv, contractile vesicle; N, nuc- 41 j- 



leus; p.pseudopodia; VIL, vmous tuft, at the ordinary temperature,, 



Fio. 289. 



EC 



VIL 



