CONTRIBUTIOXS TO THE CYTOLOGY OF THE BxVCTERIA. 435- 



osmic or formalin fixation aud Giemsa staining. This caxh 

 easily be seen by anyone who will compare figs. 117 and 118 

 with the figures which I have already published (Dobellj 1909). 

 The cytoplasm has a uniform appearance — no granular or 

 alveolar structure being apparent. In each cell a darkly 

 staining filament (cf. fig. 117) can be seen. Tliis filament 

 usually has a more or less strongly marked spiral or zig-zag 

 disposition, and extends throughout nearly the whole length 

 of the cell. Its behaviour during cell-division and spore- 

 formation I have already described in detail (Dobell, 1909). 



In my previous papers I described this filament as a 

 nucleus. As I now believe that this interpretation is com- 

 pletely justified froui my subsequent observations/ I shall 

 continue to refer to this structure by this name. I will say 

 no more about the nucleus of B. spirogyra here, as I have 

 already discussed it at some length in my previous papers, 

 but I will now pass to a description of some other Bacteria 

 which possess the same kind of structure. 



(2) Bacilli of the spirogyra type from Lacerta 

 muralis. — In my description of the cocco-bacillar forms 

 which I found in the gut of Lacerta muralis, I pointed out 

 (p. 422) that many cocci and cocco-bacilli showed nuclei of a 

 more or less spiral form (cf. fig. 50, PI, 17). Larger 

 Bacteria of a more definite bacillar form show an even, 

 greater structural resemblance to B. spirogyra. 



In the first place, there is a large Bacillus, which I found 

 very frequently in the lizards whose rectal contents I examined,, 

 which is almost identical — as regards structure — with the B. 

 spirogyra which I found in English frogs and toads. It is. 

 a large motile oi-ganism (figs. 55-60, PI. 17), rod-shaped, 

 with rounded ends, aud reaches a length of 9 /x or slightly 

 over. Dividing forms frequently exceed 10 /n in length. 



The nucleus — as in B. spirogyra — is in the form of a fila- 

 ment of chromatin, arranged in a more or less spiral or zig- 

 zag manner. It may be almost linear (fig. 55), thrown into a 

 few coils (fig. 57), or much contorted (fig. 60). Sometimes 

 ' See disciassiou on p. 466, et seq. 



