1916] Swczij: KinrfoiiHclcxs of Flagellates 197 



flagellates today, to stantl in no necessary chronological sequence, and 

 not to have the mitotic significance assigned to them by Sehaudinn. 



The main evidence rests on the presence of the "centrodesmose" 

 or "central spindle," which is neither more nor less than the con- 

 necting fibril between the nucleus and blepharoplast found through- 

 out a number of the Mastigophora. In no well-founded case has the 

 connecting fibril been shown to be formed by a centrodesmose. Its 

 connection with the karyosome also is a not uncommon occurrence 

 (Hartmann and Chagas, 1910; Chagas, 1909; Kofoid and Christian- 

 sen, 1915). If this course of reasoning holds we should expect to 

 find that the blepharoplast of Spongomonas uvella, Cercomonas parva 

 (Hartmann and Chagas, 1910), Trichomonas (Kofoid and Swezy, 

 1915a), and many other forms, would also arise by a "heteropole 

 division" of the nucleus, with the central spindle remaining as the 

 connecting rhizoplast, a conclusion which is, on the face of it, absurd, 

 and for which there is no satisfactory evidence. 



Indeed, Hartmann, in his attempt to confirm these observations of 

 Sehaudinn 's, has even claimed that "die Geisseln der Binucleaten 

 werden, wie Sehaudinn und Prowazek zuerst fiir Trypanosomen ge- 

 zeigt haben und Hartmann, Rosenbusch und Chagas vollauf bestiiti- 

 gen durch heteropole Mitose des Blepharoplasteu gebildet." 



The developmental foi'ms of trypanosomes as they have been 

 figured by many investigators (Dolflein, 1910, Minchin and Thomson, 

 1915), show the presence of both nucleus and parabasal body in 

 minute forms resulting from schizogony, as indeed throughout the 

 complete life-cycle. This is also the case in the cultural forms ob- 

 tained by Rosenbusch (1909). Prowazek 's work (1905) on Tnjpano- 

 soma lewisi and T. brucci, though based entirely on the unreliable 

 Giemsa method and with many of his figures somewhat difficult to 

 interpret, in nearly every case shows the presence of both structures. 



There is no evidence in these many figures of a single instance of 

 the origin of a parabasal body by heteropole division of the nucleus. 

 It is rather a permanent cell organ. Its origin after the still much 

 sought sexual stage is as yet unknown. 



Chagas (1909) claims to have found sexually differentiated forms 

 in Schuotrypanum cruzi. In one form the blepharoplast and flagelluni 

 are lost before the organism begins to round up at the beginning of 

 the process of schizogony. In the other case it unites with the nucleus. 

 His figures, however, do not bear out these conclusions. His plate 10, 

 figures 1-3, with merozoites in the blood corpuscles, which do not 



