76 BRITISH FRESHWATER RH1ZOPODA. 



including desmids and other algee, and sometimes also 

 rotifers and entomostraca. 



Such a mass of foreign matter renders a study of 

 the physiological structure of this organism difficult in 

 adult individuals ; but in younger examples, sometimes 

 though rarely met with, the body-substance being 

 transparent, the " shining bodies," of rounded or oval 

 figure, can readily be seen, imbedded in the hyaline 

 and homogeneous protoplasm, besides numerous vesi- 

 cular spaces, lying, as described by Green , in the 

 richly-granular intervening substance, the whole not 

 unlike Actinojphrys Eichliornii, but not so regular or 

 compact. The vesicles vary in size, and their place 

 in the protoplasmic substance is subject to constant 

 change, such change being governed by the move- 

 ments of the organism. In addition to the elements 

 described, there are always present, in this species, 

 rod-like bacteria scattered through the protoplasm in 

 great numbers. 



Greeff remarks that the body, in Pelomyxa palustris, 

 consists of pure protoplasm, and is composed of two 

 strata an outer cortical one and an inner parenchyme. 

 The former is hyaline and homogeneous ; it is the 

 chief seat of contractility, and hence in it the loco- 

 motive power resides. The whole inner parenchyme 

 is of thinner consistence and is but passively moved ; 

 it is richly granular and filled with watery vacuoles, 

 often so crowded that the substance appears reticu- 

 lately interrupted. The two strata are not sharply 

 marked off, but pass gradually into one another. In 

 the so-composed body-mass there occur, then, three 

 structures (1) nuclei ; (2) hyaline and homogeneous 

 bodies of roundish, ovoid, or irregular figure, and glossy 

 appearance (the glanzkorper) ; and (3) fine bacilliform 

 bodies. These have for some time been regarded by 

 most authors as symbiotic bacteria, and that this is 

 their true nature has now been proved. 



P. palustris is multi-nucleated. The nuclei are 

 small and obscure ; irregularly distributed between 



