84 FRESH-WATER RHIZOPODS OF NORTH AMERICA. 



Occupying the central portion of the endosarc, and mingled with the 

 food-balls, in different individuals, there is a variable quantity of other 

 globular elements of different kinds. Frequently a large proportion of 

 these globules consist of clear oil-like drops of homogeneous liquid resem- 

 bling similar globules in Pelomyxa villosa. Others appear faintly granular 

 in structure, and may be either nuclei and food-balls, or perhaps both. 

 Many globules also are simple water-vacuoles, varying greatly in number 

 and size. 



I have not been able to detect in Dinamceba, except perhaps in a few 

 young individuals, a distinct nucleus, such as is usually so conspicuous in 

 Amoeba proteus. It is not improbable that a nucleus like that of the latter 

 may ordinarily be present, and be completely obscured by the abundant 

 food and other constituents of the endosarc. 



A conspicuous contractile vesicle, like that habitually present in 

 Amoeba proteus and other species, is rarely to be seen in Dinamceba. Mostly 

 several small clear globules, up to half a dozen, may be seen from time to 

 time at the posterior extremity of the animal, which appear to substitute the 

 usual single contractile vesicle of other amoeboid forms. These globules 

 remain separate, slowly enlarge, and collapse more or less successively, in 

 the manner of the ordinary contractile vesicle. Perhaps also as a substitute 

 for the more conspicuous contractile vesicle, in Dinamceba we observe the 

 frequent displacement, from the central mass of the endosarc, of one or more 

 large vacuoles, which appear within the posterior extremity, and after a 

 little while discharge from the body their mingled liquid and solid con- 

 tents, the remains of the food. 



Though indefinite granular matter, apparently derived from decaying 

 vegetal substances, is taken with other food, Dinamceba appears not to 

 swallow sand or other conspicuous inorganic particles. 



Crystals also appear not to be present as a constituent of the endosarc 

 of Dinamceba, nor did I ever detect within it minute rods or vibrio-like 

 bodies, such as are frequently observed in some forms attributed to Pelomyxa 

 villosa. 



As before intimated, Dinamceba is a gluttonous animal, and, when 

 found under favorable circumstances, is usually observed gorged with food. 

 It appears mainly to feed on alga?, and its favorite food consists of the 

 common desmids Didymopriwm grevillii and Bambusiita brebissonii, especially 



