468 Dr. R. Greef on the Structure and 



I was enabled most definitely to observe both the external 

 circumstances (^. e. the rosette-formation and gemmiform 

 unions) and the inner changes of the nucleus accompanying 

 or rather proceeding from these, in Garchesium polypmum. 



In the first place, in the nucleus, which, in Garchesium 

 polypinum^ is usually very long and bent and twisted like a 

 worm (PL XIV. fig. 1, w), I frequently saw appear those 

 clear, usually double-contoured, nucleoles which Stein had 

 previously observed in Vorticella microstoma^ and which 

 often jDroduce the impression of nuclei with large nuclear 

 corpuscles (fig. 2). In others the whole nucleus was broken 

 up into separate segments of a roundish or oval form, which, 

 however, were still surrounded by the common membrane of 

 the nucleus, and also placed together in the form of the 

 original nucleus (fig. 3). In the interior of the individual 

 segments, again, there were several of the above-mentioned 

 nucleoles (fig. 3, /) . Lastly, in other individuals the membrane 

 of the nucleus was evidently broken through, and the whole 

 contents evacuated into the body-cavity. Sometimes larger 

 and smaller oval or round disks representing the nuclear 

 segments (PI. XIV. fig. 4), but containing a comparatively 

 far larger number of nucleoles than before, swam about — some- 

 times individual nucleoles already separated from the common 

 envelope, and then sometimes enlarged three or four times. 

 The larger nucleoles, especially when oval, again produced ex- 

 actly the impression of hard-shelled ova (PL XIV. fig. 4, a). 



In discussing the above observations I must in the fu'st 

 place remark that by these, as by Stein's observations, I have 

 not attained to any complete and clear insight into the significa- 

 tion of the "gemmiform conjugation," as Stein called it, and 

 therefore do not at present venture to append to them definite 

 ideas and consequences, as Stein has done, especially as I 

 have detected exactly the same alterations of the nucleus 

 which I have described above, on the whole in accordance 

 with Stein, as the results of gemmiform union, where I could 

 not discover, either on the individuals in question or in the 

 whole colony of Garchesium^ any external trace of gemmiform 

 unions, which of com'se does not exclude the possibility that 

 such unions may have previously taken place. Stein even 

 goes so far as to assume that, by swarming forth, such indi- 

 viduals of the stock as have completed the gemmiform union, 

 and in consequence of this are filled with the products of the 

 nucleus (called by him the placenta)^ might give origin, by 

 adhesion and renewed colonization, to the building up of an 

 entire stock, the individual members of which, of course pro- 

 duced by bifission from those first formed, are all provided 



