THE SPIROCHETES 155 



In S. balbianii there is a small cap or nodule at each end of 

 the periplast, and a dot of a similar nature at the ends of 

 S. anodontce (fig. 2, a, b, c, d), which stains red with Giemsa's 

 solution and gives the chromatin reaction with haematoxylin or 

 gentian violet. Such has been called a basal granule (fig. 2, a ; 

 b.g.) and it consists of chromatin-like substance from which in 

 S. anodontce (fig. 2, b) arises a short, stiff process which is not 

 motile, and so is not a flagellum. 



Spirochaetes divide longitudinally, that is, in the direction of 

 their long axis. In this respect they resemble Trypanosomes 

 and other flagellate Protozoa. Transverse fission is also known 

 among these organisms, and has been definitely recorded in 

 S. balbianii (5, 6), and S. duttoni (2, 3); a characteristic in which 

 Spirochaetes resemble most Bacteria. 



The full details of longitudinal division have been described 

 only recently, and that more especially in S. balbianii and 

 5. anodontce. The first structures or " organellas " to show 

 signs of division are the basal granules and membrane (fig. 2, c, d). 

 The basal granule at each end divides, and a double membrane, 

 each part with its myonemes, is seen. Breaking apart occurs at 

 one end, and the free ends gradually diverge like the legs of a 

 pair of compasses (fig. 2, e). Finally division is completed at 

 the hitherto undivided end. 



Encystment has been described by Perrin (6) in 5. balbianii, 

 and it has been suggested that the appearances seen in certain 

 other Spirochaetes may be thus explained ; but the question of 

 encystment in Spirochaetes in general is doubted by some 

 authors, as is also conjugation. 



Similarly, it has been stated that gametes occur in S. balbianii, 

 S. gallinartim, etc., narrow forms being regarded as males, wider 

 forms as females. But these appearances can be otherwise 

 interpreted, the male and female forms being merely the extremes 

 in a more or less continuous series. 



Having given now an account of the structure and the life- 

 history, so far as is known, of a typical Spirochaete, we may 

 consider broadly the position of Spirochaetes in classification, 

 and some points connected therewith. The present writer 

 recently tried various tests to endeavour to determine the nature 

 of the cuticle or periplast. This was very difficult to accomplish 

 definitely, because of the smallness of the organism, the small 

 quantity of material which was available, and the vague and 



