450 C. CLIFFORD DOBELL. 



tion of the figures on PL 18 will give a better idea of the 

 various modifications which occur in this filameut than pages 

 of description. 



The filament is a morphological element present in each 

 cell. It is a body which is independent of the walls of the 

 cytoplasmic alveoli : that is to say, it is not merely an acci- 

 dental appearance due to portions of the alveolar walls taking 

 up the stain moi-e strongly than others. It can be seen in 

 many cases that the filament crosses the alveoli, and is a quite 

 independent structure (cf . figs. 96, 102, etc.). I believe there 

 can be no doubt whatsoever that it is a structure of precisely 

 the same sort as occurs in B. spirogyra and so many other 

 similar organisms. 



Additional evidence in support of this view is derived from 

 a study of the behaviour of this filament during cell division. 

 Just as in the Bacilli of the spirogyra type, division of 

 the filament precedes division of the cell as a v/hole (see fig. 

 108). After the filament has divided into two appi-oximately 

 equal parts, the cell divides across the middle (figs. 97, 98). 

 It will be noted that during division the filament nuist lie in 

 a central position in the cell, and that immediately after 

 division it must occupy a more terminal position in the 

 daughter-cells. This no doubt to a large extent explains the 

 variable position of the filament, in different cells, alluded to 

 above. On purely morphological grounds, therefore, it seems 

 to me justifiable to regard the filament in these vSpirilla as 

 a nucleus of the same sort as occurs in Bacilli of the 

 spirogyra type. I shall discuss these filaments and their 

 interpretation later (see p. 46G) : for the present I wish 

 simply to establish the fact that a filament of this sort is 

 present in these Spirilla and in many Bacilli. 



Occasionally darkly staining granules are present in the 

 cytoplasm of the Spirilla from the lizard. They are few in 

 number, and not a constant morphological feature of the 

 cell (cf . figs. 101, 102). I regard them as probably composed 

 of reserve material of some sort. As a rule these organisms 

 are free from ofranular inclusions. 



