304 GRIFFIN. 



. Tlie radiating granules about the bases of the sensoiy bristles have 

 been mentioned. There are several references in the literature to these 

 structures, which appear to be peculiar to the Euplotidse, and the ques- 

 tions of their nature and exact location are still unsettled. The granules 

 have been observed by Dujardin, Claparede and Lachmann, Stein, Eees, 

 Stokes, and recently by Minkiewicz. Bees suggested that they might 

 be vacuoles, possibly contractile. Biitschli considered that they were 

 more likely to be pellicular formations. ]\Iinkiewicz denies that they 

 can be pellicular, or vacuoles; his statement is that they are "probably" 

 crystalline, and "probably" lie between the ectoplasm and endoplasm. 



The granules are extremely variable in size, although those of the 

 ventral surface (excepting those of the lateral row) are always much 

 smaller than those of the dorsal. The granules along the sides of the 

 adoral zone are smallest of all. 



The gramdes are always longer than broad, sometimes three or four 

 times so; colorless, refringent, and crystalline in their appearance. No 

 angles are visible, all sides and the ends apparently being smooth and 

 rounded. The largest granules of the dorsal surface may be 1 /x by 2 jx.. 

 More commonlj' the length is three or four times the width. The 

 smallest ones are not more than, one-quarter the size of the larger. The 

 gTanules of the ventral surface, except those of the lateral row, are 

 rarely more than 1 /t in length, and usually about -^ /*. 



The granules always lie around the bases of the sensory bristles, on 

 both the upper and lower surfaces, arranged radially with the base of 

 the bristle as a center. The central ends of the granules are also di- 

 rected toward the surface of the bodj', giving a conical form to the group. 

 In many instances the pellicle is actually elevated a trifle over the group 

 of granules, which fact has caused Stokes to interpret them as appear- 

 ances due to star-shaped elevations of the surface instead of real bodies. 



The number of granules in a group varies greatly, but the largest 

 gi-oups are always found on the dorsal surface, while the smallest are 

 seen in the rows beside the adoral zone. In the former there are fre- 

 quently as many as a dozen granules, while the latter rarely contain 

 more than four verj^ small ones, and frequently only one or two. There 

 is surprisingly little irregularity in the position of these groups of 

 granules. Ver}^ rarely one observes a few irregular groups in the center 

 of the ventral surface, but nowhere else. 



The granules lie in the outer layer of ectosarc, immediately beneath 

 the pellicle. They are not pellicular structures, as Biitschli considered 

 them, neither do they lie between the ectosarc and endosarc. The pres- 

 ence of the large ectosarc alveoli makes it possible to determine the 

 position of the granules by focusing in either living or stained raatei'ial, 

 and I have also found a few in sections. 



The suggestion of Eees that the groups of granules are vacuoles. 



