GENUS IIYALOSPHENIA— HYALOSPHENIA PAPILIO. 135 



trally by a large, spherical, clear or pale granular nucleus ; in different 

 specimens ranging from about j^th to j^th of an inch in diameter. 



In the vicinity of the nucleus, at the periphery of the sarcode mass, 

 there may be detected several contractile vesicles. From two to four are 

 frequently seen at the same time together. They generally expand to 

 about „„ IHI th of an inch in diameter before collapsing. 



Below the position of the nucleus, between it and the clear sarcode 

 contiguous to the mouth, the endosarc is occupied by variable quantities 

 of brownish food-balls, vacuoles, and occasionally distinct algous forms, 

 intermingled with the constituent elements. 



Green algee swallowed as food, unless of comparatively large size and 

 more peculiar shape, are not usually distinguishable among the materials 

 of the endosarc in consequence of their being obscured by the abundance 

 of constituent chlorophyl corpuscles. Among them there may occasionally 

 be seen a diatom, a desmid, or a fragment of an oscillaria. The endo- 

 chrome of the algse, as a result of digestion, appears to become shriveled 

 and assumes a decidedly yellowish or reddish-brown hue. 



The brownish food-balls vary in quantity and size. They are mostly 

 granular, but sometimes have an oleaginous appearance, and lie free in the 

 endosarc or are contained in vacuoles. They appear to be accumulations 

 of food in the process of digestion, or the remains of food which have 

 undergone digestion and are ready to be discharged. 



The vacuoles vary in number and size, sometimes few, sometimes many, 

 and ranging from 30 y th to J^th of an inch They appear as globules of 

 clear colorless liquid, of pale colorless granular matter, or of colored food- 

 balls surrounded by a stratum of either or both of the former. 



At times one or more of the vacuoles may be seen slowly approaching 

 the mouth of the shell, on reaching which their contents are discharged. 

 Food-balls, in like manner, without being enclosed in vacuoles, may be 

 seen pursuing the same course. 



In the vicinity of the mouth not unfrequently vacuoles may be seen 

 to appear, to gradually enlarge, and then collapse, in the manner of the con- 

 tractile vesicles so constantly occupying a position at the upper part of the 

 sarcode mass. 



With the other materials of the endosarc there are numerous colorless 

 well-defined granules which resemble starch, also man) r small pale globules 



