CONTRIBUTIONS TO THE CYTOLOGY OF THE BACTERIA. 437 



does cot in any way affect the fact that all the different forms 

 exist. I have represented some of the small bacillar forms in 

 fig". 51 (PI. 17). They are so closely similar to the ordinary 

 spirog-yra forms, that it will be unnecessary to enter iuto 

 a minute description of them. I would emphasise the fact, 

 however, that many organisms exist which are intermediate 

 in size and structure between these forms and the cocco- 

 bacillar foi-ms (fig. 50) on the one liand, and the long spiro- 

 gyra forms (figs. 55-00) on the other. The importance of 

 this fact will be discassed later (see p. 484, et seq.). 



Amongst the smaller bacilli inhabiting the large intestine of 

 L. mural is is a form which — though not of the characteristic 

 spirogyra tyY>e — niay conveniently be described here. The 

 organism (figs. 53, 54, PI. 17) is a short rod, about 3 // in 

 length. Each cell contains a nucleus in the form of a short, 

 straight chromatin rod (fig. 53). This rod divides in the 

 process of cell division (fig. 54), behaving like the spiral 

 filameut of ordinary spirogyra forms. This form is of 

 interest because it is but a little removed from many of the 

 cocco-bacillar forms. It may, indeed, be derived from a coccus- 

 form by simple elongation. It is — structurally — a drawn- 

 out coccus such as those in fig. 45, the nucleus assuming a 

 straight I'od-like shape instead of the spiral or zig-zag of 

 many cocco-bacilli (cf. fig. 50). Some similar organisms 

 from another lizard are shown in fig. 109 (PI. 18). The 

 drawings were made from a preparation fixed with sublimate 

 alcohol and stained with Heidenhain. Inside each cell a 

 short, darkly stained rod can be seen. I interpret this as 

 the nucleus, though it may possibly be a spore-rudiment. In 

 the case of the previously described individuals (figs. 53 and 

 54), however, such an explanation can hardly be advanced. 

 For the deeply staining rods are present in forms which are 

 undergoing division (fig. 54) and divide into two transversely 

 during this process. 



Another form of Bacillus which I found is one of large 

 size (up to 8 fx in length) which has its nucleus constantly in 

 the short, thick varicose condition which can sometimes be 



