No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 403 



ined. Form : elongate, slightly larger at one end than the 

 other, the thinner end sometimes flattened, slightly curved or 

 sickle-shaped ; the greatest diameter is found in the region of 

 the nucleus, which is situated nearer to the larger than to the 

 smaller end ; both ends of the animal are rounded. In one 

 individual (Fig. 2) the surface of the body was slightly furrowed 

 in a spiral direction. Nucleus large, with a very thick mem- 

 brane, and seldom oval, usually irregular in outline. In a single 

 case (Fig. i) two nuclei were present in one gregarine (the 

 youngest individual seen), the two nuclei were of unequal size, 

 though each contained a single nucleolus. KoUiker ('49) has 

 described a gregarine with two nuclei ; I am unacquainted with 

 any other cases. Sporocysts were not observed ; but in one 

 case the cytoplasm was quite densely filled with minute spher- 

 ical and oval bodies, which stained lightly with eosin, and in 

 each occurred a small granule (this staining with haematoxy- 

 lin) ; in the same individual a normal nucleus was also present 

 (Fig. 4). These small bodies cannot be other than spores, even 

 though they occur in the endoplasm of a gregarine in which 

 a nucleus occurred at the same time ; this observation stands in 

 no accord with what has thus far been described of the sporu- 

 lation among gregarines, and I am thoroughly at a loss to 

 explain the phenomenon. These gregarines occurred only in 

 the posterior intestine of Linens, but were not present in all 

 the individuals of this nemertean sectioned. The absence of 

 synzigia, the transverse furrows of the body, and the oval-shaped 

 spores would relegate this form to the neighborhood of the 

 genus Gonosp07-a of Schneider.) 



In the smallest nuclei found (the size of the nucleus stands 

 in some degree in proportion to that of the animal) only one 

 nucleolus was present (Figs. 3 and 5) ; in all the larger nuclei 

 their number varied from two to four, though since four nucleoli 

 were found in only two cases, two or three nucleoli may be 

 regarded as the usual number in the larger individuals. As 

 an inspection of Figs. 3-19 shows, the comparative size of 

 the nucleoli within the same nucleus is very variable, and the 

 nucleoli of one nucleus are always of unequal size. When only 

 two nucleoli occur, one is about one-half or three-quarters the 



