24 Mr. H. J. Carter on Freshwater Rhizopoda 



in process of digestion. Thus there are no chlorophyll-cells as 

 in D. pyriformis, but small brown cells, yellow oil-globules, and 

 reproductive cells, all of which do not appear in the latter, un- 

 less, as above stated, I have mistaken the " reproductive cells " 

 in D. pyriformis for large starch-granules, which the sequel will, 

 I think, make probable. Let us now review these parts more in 

 detail. 



1. Small brown cells (PI. I. fig. 6i). These are globular in 

 form, filled with granular protoplasm, and about -j-oVo-th of an 

 inch in diameter, not near so numerous or so striking as the 

 chlorophyll-cells in D. pyriformis, although they, with the 

 yellow oil-globules, appear to give the hght brown colour to the 

 species. 



2. Oil-globules (c) . These are more striking than in D. py- 

 riformis, from their constant presence, greater numbei-, and 

 bright amber-colour : they vary in size, and, under the appli- 

 cation of a solution of iodine in iodide of potassium, lose their 

 yellow colour, but only to become more brilliant and refractive. 



3. Starch-granules {d) and nucleus (fig. 6). The same as in 

 the green specimens of D. prjriformis, where the latter has be- 

 come spheruliferous. The nucleus is also about the same size, 

 (the 7-B-rSt part of an inch in diameter), but the spherules more 

 marked and sometimes granulifei'ous. As the nucleus in all the 

 specimens which I examined, and which were very numerous, 

 was in the same condition, while in its original state it probably 

 bore the usual appearance, viz. a circular discoid body (the 

 nucleolus) attached to the inner surface of a larger translucent 

 and spherical cell (the nucleus), it may be that this is the state 

 in spring, and the former the autumnal one, indicative of the 

 time of the year at which the animal generates. 



4. lleproductive cells (<?,/). These are certain cells of an 

 oval or circular shape, filled with homogeneous contents, colour- 

 less, more or less refractive, and generally about vouth of an inch 

 in diameter, but varying to twice this size or more, even in the 

 same animal. They also vary in number, from ten to twenty or 

 more, and have been seen frequently both with and without the 

 presence of the nucleus in its spheruliferous condition. On the 

 application of iodine, they, for the most part, assume a light 

 amber colour, and sometimes present granuliferous contents (/), 

 which distinguishes them at once from the starch-granule; but 

 they also present occasionally a claret-colour, although never so 

 deep or with such homogeneous contents as the starch-granule. 



As before stated, I suspect that these cells also exist in D. pyri- 

 formis, and that I have mistaken them there for large starch- 

 granules. 



In no instance have I yet found the body of D. compressa 



