SOME OBSERVATIONS ON A NEW GREGAEINE. 269 



enlarges proportionally until almost the whole of the conical 

 knob which forms the epimerite is clear of granules. During 

 this process all three divisions of the endoplasm are still quite 

 distinct. By the time this stage has been reached osmosis 

 asserts itself, and the vacuole formation mentioned above 

 commences (fig. 2). In sections, however, the free-lying 

 sporonts all show a curious thickening of the extreme anterior 

 end of the epimerite, which behaves towards stains in the 

 same way as the rest of the cuticle, being, in fact, a thickening 

 of the latter anteriorly (fig, 6). It seems a feasible explana- 

 tion of this structure to say that it represents the cuticular 

 constituents of the numei'ous processes of the epimerite, which 

 have been retracted on the animal becoming free. It may 

 here be mentioned that Liihe (14), in his review of the 

 gregarines generally, pronounces in favour of the casting off 

 of the epimerite as the typical way in which the cephalonts 

 become free. 



The nucleus lies in the deutomerite. It consists of a nuclear 

 membrane enclosing a clear ground substance, in which lie a 

 large vacuolated karyosome and a number of masses of 

 chromatic substance (fig. 7). The specimens from which 

 figs. 3 and 4 were drawn Avere very faintly stained owing to 

 excessive washing out, but some other preparations stained 

 with Grreuacher's carmine confirm the appearances ^seen in 

 sections, especially as regards the vacuolated nature of the 

 karyosome. The nuclear area is about 18^ in diameter; the 

 karyosome measures about 8 /./, and as a rule contains one 

 very large vacuole and several small ones. The large 

 chromatin masses are scattered irregularly throughout the 

 nucleus, and are of varying shape. The nuclear membrane 

 is well marked, and in common with the karyosome and the 

 chromatin masses stains deeply with both Delafield's h^ema- 

 toxylin and Heidenhain's iron-hsematoxylin. 'J'he ground 

 substance takes on a very faint blue tinge with iron-hasma- 

 toxylin. In some of the sections the karyosome has yielded 

 almost completely to the differentiating iron alum, and appears 

 gi'ey by contrast with the black chromatin masses. In 



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