136 FRESHWATER RHIZOPODS OF NORTH AMERICA. 



resembling vacuoles, and in addition oil-like globules of various sizes, 

 sometimes colorless and sometimes yellowish in hue. These latter mate- 

 rials especially are obscured by the chlorophyl corpuscles. 



The pseudopods are digitiform and from two or three to half a dozen or 

 more in number. They sometimes extend to a length of —th of an inch 

 with a thickness of gith of an inch. They are usually simple, but occa- 

 sionally branch, and are blunt at the end. They are colorless, and with 

 high powers can be seen to be finely but faintly granular throughout. The 

 coarser granules of the endosarc do not enter them. 



As the pseudopods protrude, the mass of the sarcode in the interior of 

 the shell proportionately diminishes, and the threads of attachment are put 

 to a greater stretch. When the animal is disturbed, the pseudopods are 

 retracted, but the sarcode mass commonly retains its attachment to the 

 mouth of the shell. Occasionally, however, when the animal is suddenly 

 or rudely disturbed, the sarcode mass retreats far into the shell, as repre- 

 sented in fig. 5. In proportion as the sarcode retracts or extends, the 

 attaching threads shorten or lengthen. 



Not unfrequently, but especially in October and November, and also 

 in the winter months, in sphagnum preserved in a moderate temperature, 

 specimens of H. papilio are to be seen in which the sarcode mass forms 

 a compressed spheroidal ball lying completely quiescent within the shell, 

 as represented in figs. 7-11. The ball, in the narrower view of the latter, 

 is seen to touch the sides, but in the broader view does not extend to 

 the lateral borders. The ball ranges from ith of an inch to 3 J th of an 

 inch in breadth, and ^th to ^ th of an inch in thickness. Generally it is a 

 little greater in its longitudinal than in its broader transverse diameter. 

 The constitution of the ball appears to be nearly the same as the sarcode 

 mass in the active animal, but is devoid of the materials recognized as food, 

 and also presents no vacuoles nor contractile vesicles. It is bright green 

 from the presence of abundance of chlorophyl corpuscles, which exist in 

 the same proportion as usually observed in the active condition of the animal. 

 A central clearer spot would appear to indicate the retention of the nucleus. 

 The exterior of the ball is composed of a layer, of variable thickness, of 

 colorless, faintly granular ectosarc, not defined from the granular endosarc 

 extending into the mass of chlorophyl corpuscles. Occasionally the green 

 sarcode ball is invested by a more distinct and colorless membrane. 



