E. Hindle 
465 
The various stages are shown in the accompanying text figui’e 
(Fig. 1). One end of a loug spirochaete (a) doubles back (b), the 
reflexed portion being closely applied to the main part of the parasite. 
The reflexed part gradually increases in length (c), all the time being 
closely wound round the other portion of the spirochaete {b, c), and thus 
the two ends approach each other and finally appear in juxtaposition 
(d). The appearance now presented by the parasite is that of two 
spirochaetes tightly coiled together, except that at one end of the coil the 
two threads are continuous, being flexed through an angle of 180°. 
After having passed through this process, which takes place with 
considerable rapidity, the two halves of the spirochaete uncoil from each 
other ( f, g) and separate at the point of flexion {g), thus producing two 
parasites. Sometimes the spirochaete breaks in two, before the daughter 
parasites have uncoiled from each other (e). In the former case the 
parasites may remain connected together for some time before finallj 
separating {li) and in this case exactly resemble the forms of transverse 
division previously recorded for these parasites. 
As the two halves of the dividing spirochaete are very closely wound 
together before separating, the process of unwinding and final separation 
into two halves simulates longitudinal division to an extraordinary 
degree and, in many cases, it required the most careful examination to 
decide whether one was dealing with a case of true longitudinal division, 
or the above described transverse fission. I have never observed 
longitudinal division in either this species or S. duttoni, and it seems 
probable that the so-called “ longitudinal fission ” might be explained as 
the final stage of this peculiar method of transverse division. As for 
those cases in which an apparently single, long spirochaete merely 
separates into two approximately equal halves, it is impossible to say 
whether they represent the last stage of the above-described division, 
or merely the separation of two distinct parasites which have been 
temporarily agglutinated together by their ends. It may also represent 
direct transverse division without any previous flexion of the spiro¬ 
chaete. 
In any case, whatever may be the true interpretation of the latter 
forms, the division of S. gallinarum is certainly usually transverse, and 
as I have devoted considerable time to the observation of the parasite 
without ever having observed any sign of longitudinal fission, I believe 
that it is invariably transverse. 
By means of examination with the dark-ground illumination, I have 
frequently observed the breaking up of the spirochaete into a number 
