COXTKIBLITloNS TO THE CYTOLOGY OF THE BACTERIA. 461 



observations in no way invalidate the contentions of Yejdovsky 

 and Mencl regarding- Bacterium gammari. I see no reason 

 at pi-esent for doubting that this organism belongs to the 

 Bacteria. My own investigations have shown merely that 

 certain organisms, which appear to resemble B. gammari 

 at one stage in their lives, are really not Bacteria at all, but 

 belong to the Funo-i. 



Summary of Results. 



I will now summarise the results which I have recorded in 

 some detail in the foregoing pages. In this section I shall 

 consider my own work only, without reference to the work of 

 others. A full discussion will be found in the next section of 

 the paper (p. 462 et seq.). 



(1) All the Bacteria which I have been able to investigate 

 with pi'ecision contain a structure (or structures) which I 

 believe to be a nucleus. The reason for regarding these 

 structures as nuclei is two-fold — first, from purely morpho- 

 logical considerations; secondly, from their staining reactions 

 (see discussion, p. 462). 



(2) The Bacteria studied belong to four different groups — 

 namely, Cocci, Bacilli, Spirilla, and so-culled '' fusifoi-m 

 Bacteria." 



(3) The Coccus forms studied possess a single, centrally 

 placed, spherical nucleus in each cell. It divides by a 

 simple amitosis. This type of nuclear organisation has been 

 found informs belonging to the genera Micrococcus and 

 S a r c i n a . 



(4) Cocco-bacillar forms which have been iuvestigated 

 show a nucleus in the form of a straight or bent rodlet, or of 

 a njore or less spiral or zig-zag filament. 



(5) Bacillar forms show several different types of nuclear 

 differentiation. The nucleus may be in the form of chromidia 

 scattered through the cell (flexilis type, etc.) ; in the form 

 of a more or less straight, spiral or zig-zag filament 

 (spirogyra type, etc.) ; or in the form of irregular strands 



