GENERAL CHARACTERS OF SPIROCILETES. 21 



ance of this fibrillary structure at the outer margins of 

 the curls presented by the spirochaste suggests that it 

 may be a portion of periplast which has become fixed 

 to the slide, and has thus remained fast, in a figure cor- 

 responding with the curves in which the creature lay at 

 the moment of death: then as drying took place and 

 the body of the spirochaete shrank, the latter straight- 

 ened out somewhat, while the adherent periplast re- 

 mained. Sometimes, however, the "membrane" runs 

 in a straight line between neighbouring coils, having 

 apparently shrunk more than the body-substance. 



Borrel and Cernovodeanu, however, state that 

 they have seen an undulating membrane in living 

 specimens of Sp. anodontcB. 



Perrin thinks that the undulating membrane is not 

 of much importance as an aid to locomotion in Sp. 

 balbianii. 



With regard to the structure of the entoplasm and its 

 contents an equal degree of uncertainty prevails. 

 Perrin described in Sp. balbianii the existence of pecu- 

 liar form of nucleus. It consists, according to this writer 

 of a spiral band of achromatic substance (karyosome) 

 on which appear at intervals masses of staining material 

 (chromatin ?) . These latter usually, in resting organ- 

 isms, take the form of rods arranged so as to lie trans- 

 versely, more or less at right angles to the main axis of 

 the spirochaete (Fig. 5) ; but when fission is about to 

 occur, the rods assume other forms and undergo divi- 

 sion. Fantham confirmed Perrin's statements. Keys- 

 selitz described in Sp. anodonta balls and rods of chro- 

 matic material (Fig. 6) , and thinks that there may be a 

 spiral arrangement such as Perrin found, but did not 

 himself observe it. Schellack confirms the existence of 

 bands of chromatin, but denies that they are connected 



