470 ('. crjri'OKi> hoiikjj,. 



for the same idea occurred to Nakanislii himself, and he 

 broug'ht forward good experimental evidence to show that 

 this was not the case. 



As a result of my researches I regard it therefore as certain 

 that the Coccus forms of Bacteria contain a nucleus 

 of the form which I have described in the earlier part of 

 this paper. 



And now let us consider the other Bacteria. I have 

 pointed out already that I have investigated a large number 

 of cocco-bacillar organisms which present every degree of form 

 between typical Cocci on the one hand, and typical Bacilli 

 on the other. Witli change in tlie external shape, the nucleus 

 shows a corresponding modification. It becomes elongated 

 with the elongation of the cell, and hence assumes the form 

 of ;i tihiment. In round coccus forms, the nucleus is round. 

 In slightly elongated cocci, the nucleus is in the form of a 

 short rodlet, which may be curved or slightly bent. In still 

 more elongated cocco-bacillar organisms, the nucleus may 

 have the form of a zig-zag or spii-al filament. These forms 

 merge gradually into the forms of the characteristic spiro- 

 gyra type. 



I have not proved that the Cocci, spirogyra Bacilli and 

 intermediate cocco-bacillar forms, which I have found living 

 together, are genetically connected. A ])roof of this is 

 immaterial for the present purposes. It suffices to know that 

 all these forms occur. Morphologically considered, therefore, 

 tlie spiral or zig-zag filament present in Bacilli of the 

 spirogyra type is the equivalent of the spherical body which 

 lies in the centi-e of the Coccus cells. Consequently, if it is 

 agreed that the latter is a nucleus, it follows that the spiral 

 filament of Bacilli of the s]nrogyra type is also a 

 nucleus. This is a conclusion which is supported by the 

 behaviour of the filament during cell-division and spore- 

 formation, which I have described in detail in B. spirogyra. 

 My study of this form indicates lieyond a doubt that the 

 filament is al i ving element of the cell, and not a metaplasmic 

 structure. 



