(JOXXraBUTlONS to the cytology of the r.ACTERfA. 449 



have found that it possesses a different kind of organisation. 

 It is — like the other forms — difficult to stain satisfactorily, 

 but I liave obtained some beautiful results with irou-hasnia- 

 toxylin. My figures (figs. 96-108, PI. 18) are all drawn from 

 wet film preparations, fixed with sublimate alcohol and stained 

 with Heidenhain's iron-hasmatoxyliii. My best prepai-ations 

 are from the contents of the large intestine of lizards which 

 I obtained from a dealer in Munich; but similar — I believe 

 the same — Spirilla also occur in Naples lizards, and have 

 furnished me with additional material. 



The structure of these Spirilla is shown iu figs. 96-108. 

 Long individuals attain a length of as much as 13 fx (fig. 102) 

 and more, whilst the shortest individuals measure about 4 /ii 

 (figs. 103-105). All forms display a structure which is 

 essentially the same, and Avhich difi'ers markedly from that 

 of other forms Avhich I have investigated. 



In fixed and stained organisms ^ the cytoplasm has, as a 

 rule, a very distinct alveolar structure (cf. tigs, 96, 100, 

 102, etc.). The alveoli may extend right across the cell, 

 being arranged as a single row of large chambers (fig. 96), 

 or they may be of variable smaller sizes (e. g. fig. 107). The 

 only other structure which is normally present in well-stained 

 individuals is a darkly staining filament, like that of B. 

 spirogyra, which I interpret in this case also as the 

 nucleus (see figs. 96-108). Both the form and position of this 

 filament may vary. It is frequently in the form of a short 

 and nearly straight rod (figs. 96, 104, etc.), occupying a 

 central (figs. 104, 107) or terminal (fig-, 96) position, or any 

 intermediate site in the cell. It may be in the forni of a more 

 or less twisted and varicose spiral or zig-zag (figs. 101, 102, 

 etc.), sometimes showing knob-like thickenings at the ends 

 (figs. 100, 105), and sometimes running almost from one 

 extremity of the cell to the other (figs. 100, 101, etc.). Inspec- 



^ As in the case of other Spirilla I have been unable to reach 

 any definite conclusions regarding structure from a study of the 

 living organisms. The living organisms, however, have been studied 

 in all cases. 



