1916] Swczij: Kinrfoiuirlcus of Flagrllafcs 193 



thrown out into the cytoplasm and dissolves; the more fluid parts of 

 the nucleus are also thrown into the cytoplasm by the dissolution of 

 the nuclear membrane." In Aequorea Hacker (1892) has described a 

 process whereby the nucleolus is cast out into the egg-cytoplasm, 

 where it degenerates. In many forms among the Metazoa it is cast 

 out during the formation of the polar bodies or it may fade away in 

 situ (Wilson, 1911). The nucleolus of the metazoan cells presents a 

 variety of staining reactions, those of the echinoderms often staining 

 deeply with chromatin stains. 



Hacker (1892) has made the suggestion that, in some cases at least, 

 the nucleoli are accumulations of by-products of nuclear activity, de- 

 rived from the chromatin and representing passive material which is 

 of no further direct use in the nucleus. 



It seems not improbable that we are dealing liere witli the same 

 sort of snl)stanee in the Protozoa. The period prior to gamete forma- 

 tion is usually one of great metabolic activity and growth, and conse- 

 quently an excess of nuclear material may result which is of no further 

 use in forming niiclei and cells, and is cast out to degenerate in the 

 cytoplasm. This explanation fits the conditions as found in Amoeba 

 and Trichomonas as well as those forms of the Foraminifera and 

 Heliozoa in .which a residue of material may remain after the forma- 

 tion of the gamete nuclei. It certainly seems a more natural explana- 

 tion than does the view of tropho- and generative chromatin which 

 has usually been applied to these conditions, based on the supposition 

 that two substances were here involved, each playing different parts in 

 the activities of cell life. No differentiation of these substances lias 

 thus far been made. It seems more probable, indeed, that it is one 

 and the same substance, combined with secretion products as the re- 

 sult of great metabolic activity at some periods in the life-cycle. 



Hartmann, in his further elaboration of Schaudinn's binuclear 

 theory, advanced the idea that all cells of the Protozoa as well as 

 Metazoa were binucleated, possessing a locomotor-generative nucleus, 

 known as the centrosome in the Metazoa, the "blepharoplast" or 

 " kinetonucleus " in the trypanosomes, the "central grain" in the 

 Heliozoa, the "Nebenkern" in Paramoeba, etc., and also po.ssessing a 

 trophogenerative nucleiis forming the definitive nucleus (Hartmann 

 and Prowazek, 1907). Pui-ther investigation revealed, as he claimed 

 (Hartmann and Chagas, 1910), that both the "kinetonucleus" and 

 the trophonucleus possessed their own centrosomes (Cytozentrum) as 

 well as generative chromatin. To meet this condition he proposed the 



