436 C. CLIFFORD DOBELL. 



it lias a iiiucli sliortened and thickened form (fig. 56). It 

 displays, in fact, the same range of variations which 1 have 

 already described in B. spirogyra. 



Division of the cell is preceded by division of the nucleus 

 into two portions (cf . figs. 59, 60), exactly as in B. spiro- 

 gyra. The organism is, inoveover, nionosporic — forming a 

 single terminal spore in each cell (fig. 58). I have not 

 followed out the whole of tlie stages in spore formation, but 

 it appears closely similar to what I have already described in 

 detail in the form from the frog and toad. (See Dobell, 

 1909.) 



These figures (figs. 55-60) are all from preparations treated 

 by the osmic-Giemsa method (p. 415). I have, however, ob- 

 tained confirmatory results by other methods. In figs. 91-95 

 (PI. 18) organisms are shown which have been fixed 

 with sublimate-alcohol and stained with Heidenhain's iron 

 hasmatoxylin. It will be seen that the structure of the cells 

 is essentially the same as in the osmic-Giemsa preparations. 

 This organism presents the same difficulties in staining by 

 i:-on-h£ematoxylin as B. spirogyra (see p. 434). The indivi- 

 duals depicted are therefore selected specimens in which 

 differentiation is particularly good. 



As in the case of B. spirogyra, there can be no ])ossible 

 doubt of the existence of the spiral filament which I regard 

 as the nucleus. Giemsa preparations reveal it always with 

 the greatest distinctness, and Heidenhain staining — when 

 successful — does the same. Though my interpretation may 

 be wrong, the structures which I have described and figured 

 ■exist beyond all shadow of doubt. 



I found a large number of organisms of the same type 

 which are intermediate in size between theforms just described 

 and the cocco-bacillar forms described on p. 422. In fact I 

 ■found such a gradually graded series of forms that it is diffi- 

 cult to me to avoid the conclusion that the smallest cocci and 

 'the largest bacilli are genetically connected. Direct proof of 

 ■this most important point is wanting. Nevertheless, whether 

 the different forms are different species or one and the same 



