78 FRESH- WATER RHIZOPODS OF NORTH AMERICA. 



food and other materials of different kinds. Usually the quantity of the 

 ingesta is so great as totally to obscure from view all the intrinsic consti- 

 tuents of the endosarc except when they rush into pseudopodal projections 

 of the ectosarc. 



The food is mainly of vegetal character, consisting of all sorts of algae, 

 especially diatoms, desmids, and other unicellular forms, oscillarias and 

 other filamentous forms, fragments of higher plants, fibres and particles of 

 wood and leaves, etc., besides flocculent, apparently decaying, vegetal matter. 

 The food in the interior of the animal, as in other amoeboid forms, when of 

 soft or yielding character, appears as variously colored balls, mostly 

 yellowish, brownish, or green, often enclosed in water-drops, but often also 

 free from the latter, as indicated by the absence of the clear zone, which 

 usually indicates the presence of surrounding liquid. Much of the food 

 apparently is diffused, as fine yellowish matter, among the intrinsic granu- 

 lar constituents of the endosarc. 



In the ordinary process of digestion in Pclomyxa villosa, as in other 

 amoeboid forms, green vegetal substances gradually assume a yellowish or 

 brownish hue. The insoluble residue of the food of all kinds is from time 

 to time discharged in the usual manner at the posterior extremity of the 

 body, but whether through or to one side of the villous process I did not 

 ascertain. 



Quartz-sand is a frequent and abundant material mingled with the food 

 and other constituents of the endosarc. Not only fine but coarse particles 

 are swallowed, but they appear always to be directly in contact with the 

 granular and other matters of the endosarc, and not contained in vacuoles 

 or water-drops, as ordinarily is the case with most solid food. In many 

 individuals, the quartz-sand has appeared to predominate over everything 

 else in the endosarc, and such specimens, which were literally bags of sand, 

 I formerly described as a species, with the name of Amoeba sabulosa. 



Pclomyxa palustris, as described by Prof. Greeff, also swallows a nota- 

 ble quantity of sand ; but this appears not to be the case, at least to any 

 remarkable extent, with Amoeba villosa, as described by Dr. Wallich and 

 Dr. Duncan. 



Dr. Wallich describes crystals of rhombohedral form as a constituent 

 of the endosarc of Amoeba villosa; but these bodies, ordinarily so conspicu- 

 ous and common in Amoeba proteus, either do not exist, or they escaped my 



