1919] Kufoid-Swczfj: Tricltomjinplia campanula 71 



becomes a huge blepharoplast complex. At the time of division the 

 entire structure divides into two parts, taking the role of centrosomes 

 in the succeeding mitotic figures, while continuing its intimate rela- 

 tions with the flagella. The term centroblepharoplast thus designates 

 the dvial functions of this organelle complex. 



Equally distinctive and typical of the phenomena of mitosis in 

 flagellates is the formation of a paradesmose couectiug the divided 

 centroblepharoplasts. In Trichomonas (Kofoid and Swezy, 1915) 

 at the occasional separation of the blepharoplasts and centrosomes 

 this structure appears to be connected with the blepharoplasts and 

 not with the centrosomes. In Trichoviitus (Kofoid and Swezy, 

 1918&), however, the paradesmose is found connecting the centro- 

 somes to which the blepharoplasts are attached by a slender rhizo- 

 plast. In this form these structures have a longer lease of life, the 

 majority of individuals noted showing the prophase stage with the 

 completion of the formation of the paradesmose. In both these 

 flagellates, as in Trichonympha, it subserves the same function in 

 mitosis with the same relative position outside the nuclear membrane. 



The heavy band connecting the two parts of the divided centro- 

 blepharoplast in Trichonympha, to which Poa (1904) has given the 

 name external spindle {fuso esterno), we consider homologous with 

 the paradesmose of the triehomonad and other flagellates, and have 

 so designated it. We have given a fuller discussion of this subject 

 in an earlier paper (1919c). 



The similarity of the paradesmose and the "sphere" of Noctiluca 

 points to an homology between them, which thus links what has been 

 considered a peculiar type of mitosis (Calkins, 1899) in the latter 

 form with conditions found among other flagellates. "Whether the 

 nuclear membrane dissolves at the points of contact with the parades- 

 mose in Trichonympha, as in Noctiluca, has not been definitely 

 ascertained, but no evidences to support such a conclusion have been 

 found. The ultimate fate of the paradesmose in both Noctiluca and 

 Trichonympha seems to be the same, that is, it fades out in the middle 

 and is absorbed or drawn up into the central mass of the centrosomes. 



In the small chromatin rod, isolated from the remaining chromatin 

 contents of the nucleus, we have a structure that is unique among the 

 Protozoa and finds its nearest counterpart in the Metazoa in the 

 "sex" chromosomes of the germ cells. Its resemblances to the latter 

 are particularly striking during the different phases of division. 



