160 SCIENCE PROGRESS 



Salvin-Moore and Breinl (9), and Swellengrebel (13) have all 

 described the presence of a filament, largely achromatic, in 

 several species of pathogenic Trypanosomes (T. brucei, T. gam- 

 biense, and T. equinutn). This filament has been variously called 

 by these writers the "central line," the "black line," and the 

 *' achromatic filament " respectively. It has been seen inde- 

 pendently by the present writer also in these species, and 

 in addition in T. evansi of Surra. 



Robertson has attempted briefly and ingeniously the homology 

 of this line with portions of the condensed nucleus of cells of the 

 higher forms, using some diagrams of hypothetical ancestral 

 flagellates given by Perrin (6). 



It might be urged that these appearances are due solely 

 to degeneration, or to the reaction of the host on the parasite. 

 In some of the cases described the infection certainly was an 

 " artificial " one — e.g. T. brucei in a guinea-pig and T. gambiense 

 in white mice. But even then, these appearances may be 

 examples of " reversion." They cannot be due merely to faulty 

 technique, for Moore and Breinl have taken the greatest care 

 with their fixation and staining. Chromatin granules, more or 

 less scattered, have long been notified in the general cytoplasm 

 of Trypanosomes. 



Again, in this connection, the moniliform character of the 

 trophic nucleus of Spirostomum is worthy of note. Here we 

 have a nucleus of a ciliate Protozoon with an undoubted like- 

 ness to the nuclear figure of Spirochceta plicatilis, according to 

 Schaudinn (fig. 1, a.). So far as I know, this relationship has 

 not been remarked on before, and it is, it seems to me, much 

 more than a mere resemblance or convergence. 



The spiral axis of the nuclear apparatus of Spirochetes seems 

 to me to be a karyosome, largely achromatic, with at times some 

 chromatin in the achromatic substance, which chromatin has 

 migrated thither in the form of granules or chromidia. The 

 chromatin is principally found as transverse rods arranged along 

 the spiral, and giving the spiral a somewhat flattened appearance. 

 In the concentrated nucleus of most Protozoa and the Metazoa, 

 this spiral is either condensed in its entirety, or only the middle 

 portion of the long helix of the Spirochete remains, the rest 

 aborting. 



Probably the latter view is the more correct, judging by the 

 number of chromosomes usually found in the cells. The oval 



