446 C. CLIl-'FOED DOBELT-. 



iovm of a short, irregular mass of chromatin, which appears 

 sometimes to be really a spiral filament contracted upon itself. 

 Fig. 17 shows a pair of Bacilli with rod-like nuclei. Fig. 18 

 appears to be a similar kind of organism undergoing division. 

 Fig'. 16 is an individual which is like a B. saccobranchus, 

 Avith a nucleus of the irregular type, on a smaller scale. 

 None of the smaller forms showed nuclei of a distinct 

 chromidial type. 



3. Spieillae Foems. 



I have endeavoured to elucidate the structure of a number 

 of spirillar forms, but have succeeded in reaching definite 

 results in only four diiferent forms. Yet these four diiferent 

 forms have shown me three different types of nuclear apparatus, 

 and these I shall now describe. 



(a) Spirilla with Nuclei of a Chromidial Type. 



In a previous paper (Dobell, 1908) I described briefly the 

 structure and method of spore-formation which is fouud in 

 the Spirillum — which I named S. monospora — which 

 occurs very commonly in the large intestine of frogs and 

 toads. I described this organism as containing a number of 

 scattered granules, stainable with chromatin stains. These 

 granules I regarded as constituting a nucleus of the same 

 sort as that of B. flexilis and similar forms. They enter 

 into the formation of the spore, forming a nucleus-like spore 

 rudiment — as in B. flexilis, B. spirogyra, B. lunula, 

 and many other Bacteria. 



I have made many attempts to obtain a more detailed 

 knowledge of S. monospora. My efforts, howevei', have 

 been unavailing. The facts — as far as they go — which I 

 have already recorded are the only ones which I have so far 

 been able to discover. I therefore abandoned this form and 

 looked for other and more favourable objects for investiga- 

 tion. 



