THE SPIROCHETES 161 



character of the nucleus of T. brucei with the transverse arrange- 

 ment of its eight chromosomes as figured by Prowazek and 

 Robertson supports this. The transverse bars of chromatin 

 in Spirochceta balbianii are, then, probably comparable to 

 chromosomes, as suggested by Perrin. 



To summarise : first we have a diffuse nucleus of scattered 

 chromidial granules as in Bacillus butschlii and many rod-like 

 Bacteria ; next, the arrangement of these granules to form a spiral 

 or helix, as in Bacillus maximus buccalis, and more clearly in 

 Spirochceta balbianii; lastly, we have the condensed nucleus of 

 Trypanosomes and the cells of the Metazoa, the connecting link 

 being supplied more especially by the work of Robertson and 

 Swellengrebel. 



This review is, perhaps, hardly the place to pursue this 

 interesting hypothesis further. Suffice it to say that the 

 study of the chromatin of Bacteria and Spirochastes suggests 

 interesting chapters in the evolution of the metazoan nucleus. 



List of References quoted 



Fuller references will be found at the end of most of the memoirs given in 



the following list. 



1. Blanch ard, R. (1906), Spirilles, Spirochetes, et autres micro-organismes a 



corps spirale, Semaine me'dicale, Paris, Jan. 3, 1906, pp. 1-5. 



2. BRElNL, A., and T .nghorn, A. (1906), An Experimental Study of the Parasite 



of the African Tick Fever {Spirochceta duttoni), Liverpool Sch. Trop. 

 Med., Memoir XXI. 



3. Dutton, J. E., and Todd, J. L. (1907), A Note on the Morphology of Spiro- 



chceta duttoni, Lancet, pp. 1523-5, Nov. 30, 1907. 



4. Ehrenberg, C. G. (1833-5), Spirochasta, n.g., S. plicatilis, n.sp., Abh. Akad. 



Berlin, p. 313. 



5. Fantham, H. B. (1907-8), Spirochceta (Trypanosoma) balbianii (Certes) 



and Spirochceta anodontce (Keysselitz) : their Movements, Structure, and 

 Affinities, Quart. Journ. Microsc. Sci. 52, i. pp. 1-73, 3 plates. 



6. Perrin, W. S. (1906), Researches upon the Life-History of Trypanosoma 



balbianii, Arch.f. Protistenkunde, vii. pp. 131-56, 2 plates. 



7. Prowazek, S. von (1906), Morphologische und entwicklungeschichtliche 



Untersuchungen iiber Hiihnerspirochaeten, Arb. a. d. Kaiserl. Gesundheit- 

 samte, xxiii. pp. 554-65, 2 plates. 



8. Robertson, Muriel (1906), Notes on Certain Blood-inhabiting Protozoa, 



Proc. Roy. Phys. Soc. Edinburgh, xvi. pp. 232-47, 2 plates. 



9. Salvin-Moore, J. E., and Breinl, A. (1907), The Cytology of the Trypa- 



nosomes, Part I., Ann. Trop. Med. and Parasitology, vol. i. pp. 441-80, 

 plates 38-42. 

 10. Schaudinn, F. (1905), Zur Kenntnis der Spirochceta pallida (Vorl. Mitteil), 

 Deutsch med. Wochenschr. No. 42, p. 1665. 



II 



