476 C. CLIFFORD DOBELL. 



that they are living structures.^ In Bacilli of theflexilis 

 type the chromidia are too small for their division to be 

 observed Avitli accuracy, but I think they probably behave in 

 much the same way as the larger chromidia of Achro- 

 m a t i u m . 



The remaikable woik of Mend (1905) upon filamentous 

 water Bacteria (Cladothrix, etc.) contains many observa- 

 tions which are in complete accord with mine. In the forms 

 investigated — which are pleomorphic — he found nuclei of a 

 spherical, filamentar, and chroniidial form, with numerous 

 intermediate forms. He was able to observe the division of 

 these nuclei in the living cells — thus proving that they were 

 really living structures, and not metachromatic or other non- 

 living granules. He believes that the different nuclear forms 

 occur, at different stages in the life-history, in the same 

 oiganism. His results are therefore closely similar to mine. 



The nuclear interpretation of the chromidial structures 

 present in Bacteria — as upheld by Schaudinu, Guilliermond 

 and myself — has been controverted by Riizicka (1909) on the 

 grounds that the whole bacterial cell is itself the equivalent 

 of a nucleus. Apart from the a priori absurdity of this 

 yiew — which I have already pointed out above — I must em- 

 phasise the fact that the observations recorded in the present 

 paper completely condemn such an interpretation. On the 

 other hand, I believe the chromidial view is completely 

 vindicated. The statement made by Ambroz, who follows 

 Ruzicka, that the chromidial view has been " reduced ad 

 absurd um" by the latter, is therefore entirely erroneous. 



The observations of Mitrophanow (1893)" seem to me to be 

 capable of being brought into line with my own, when 

 allowance is made for the difference in technique. I find it 

 not always easy to comprehend Mitropluinow's meaning; his 

 methods of fixation and staining also seem to leave much to 



' Hhrze (UHJo) made similar oLservatitms in the case of Thiophysa. 



- This j)aper is an abstract only of a larger work in Russian. It is 

 therefore possible that Mitroplianow"s observations and views are more 

 cleai'ly given in the original — wliicli is unfortiniately inaccessible to me. 



